We agree in part, but disagree in part, with the decision of the Court of Appeals. While we agree that a new hearing must be conducted by the trial court, we hold that the scope of the hearing must be extended beyond that ordered by the Court of Appeals.
I.
The primary question presented in this appeal is whether the consent order of 6 December 1976 is modifiable.
In Bunn v. Bunn, 262 N.C. 67, 136 S.E. 2d 240 (1965), this court, in an opinion by Justice (later Chief Justice) Sharp, held that there are two types of consent judgments which provide for payment of support to a dependent spouse. One is simply a contract that is approved by the court. The payments specified therein are not technically alimony. This type of consent judgment is enforceable only as an ordinary contract and the parties are not subject to the contempt power of the court for its breach. Consent of both parties is required for modification. Id.
In the second type of consent judgment, the court adopts the agreement of the parties as its own and orders the supporting spouse to pay the amounts specified as alimony. This second type of order is enforceable by the court’s contempt powers. Id. Ordinarily it is also modifiable. Bunn, supra.
In the case at hand, were it not for the proviso in the 6 December 1976 consent order that G.S. 50-16.9 would not apply, Bunn no doubt would control this case. Usually, public policy would require that the consent order be modifiable in spite of this proviso.
Our legislature in 1967 codified the principles enunciated in Bunn by enacting G.S. 50-16.9. This statute provides in pertinent part:
(a) An order of a court of this State for alimony or alimony pendente lite, whether contested or entered by consent, may be modified or vacated at any time, upon motion in the cause and a showing of changed circumstances by either party or anyone interested ....
*184By enacting this statute, the legislature has clearly expressed that it is the public policy of this state that consent orders to pay alimony are modifiable. In the usual case a proviso in an order purporting to waive applicability of G.S. 50-16.9 would be contrary to this policy and, therefore, without force and effect.
Nevertheless, this court in Bunn and in White v. White, 296 N.C. 661, 252 S.E. 2d 698 (1979) recognized an exception to the rule just stated. We quote from the opinion by Justice Exum in White:
Even though denominated as such, periodic support payments to a dependent spouse may not be alimony within the meaning of the statute and thus modifiable if they and other provisions for a property division between the parties constitute reciprocal consideration for each other.
296 N.C. at 666.
For purposes of determining whether a consent judgment may be modified under the statute, there is a presumption that the provisions for property division and support payments are separable. Id. The burden of proof rests on the party opposing modification to show that the provisions are not separable. Id.
At the hearing before Judge McHugh, defendant attempted on two occasions to introduce evidence of the negotiations between the parties in an effort to show that the consent order and property settlement were reciprocal agreements. First, on cross-examination of plaintiff, and referring to the proviso on non-modification, defendant’s attorney asked: “How do you recall that provision got into that order in the negotiating process?” Plaintiff objected to the question and his objection was sustained by the trial judge. The Court pf Appeals found no error in this ruling on the ground that admitting evidence relating to the negotiations would violate the parol evidence rule that any or all parts of a transaction prior to or contemporaneous with a writing intended to record them are superseded and made legally ineffective by the writing. Tomlinson v. Brewer, 18 N.C. App. 696, 197 S.E. 2d 901 (1973); 2 Stansbury’s N.C. Evidence § 251 (Brandis Rev. 1973).
We disagree with the trial court and the Court of Appeals that the testimony defendant sought to elicit on cross-examination would violate the parol evidence rule.
*185Generally, evidence of prior and contemporaneous negotiations and agreements are not admissible to vary, add to, or contradict a written instrument. Bailey v. Westmoreland, 251 N.C. 843, 112 S.E. 2d 517 (1960); 2 Stansbury’s § 251. However, when the court finds a contract to be ambiguous, evidence of prior negotiations is admissible to show the intent of the parties. Root v. Ins. Co., 272 N.C. 580, 158 S.E. 2d 829 (1968). Further, the rule is intended to apply only to final, totally integrated writings; that is, those writings relating to a transaction which are intended to supersede all other agreements regarding that transaction. If the writing supersedes only a part of the transaction, it is a partial integration and other portions of the transaction may be shown by parol evidence. 2 Stansbury’s § 252.
Turning to the case at bar, we reiterate that ordinarily the proviso in the 1976 consent order regarding non-modification would be without force or effect. In accord with G.S. 50-16.9, the consent order may be modified unless defendant can show that it was an integral part of the property settlement. White v. White, supra. The intention of the parties regarding the reciprocity of the agreements is not evident from a reading of the consent order. Therefore, evidence of the negotiations and contemporaneous property settlement agreements of the parties are admissible to clarify the uncertainty created when the non-modification provision of the order appears to be void as a matter of law. We also note that defendant does not seek to vary, add to or contradict the terms of the consent order. Indeed, she is merely trying to enforce the entire agreement as written.
Further, it is clear that the consent order represents only part of the total settlement between the parties. As such, it is only a partial integration of the total agreement and parol evidence is admissible to show the balance of the transaction. 2 Stansbury’s § 252.
The second effort made by defendant to prove that the consent order was an integral part of the property settlement was an attempt to introduce a letter written 18 November 19761 by plaintiff’s then attorney to defendant’s then attorney offering a settlement.
*186The letter begins “I have talked with Henry Rowe again in an effort to settle all matters existing between Henry and Mary. At this time, by way of offer of compromise and settlement on Henry’s behalf, I wish to advise the following . . . The letter lists eleven items including “3. Henry will pay to Mary alimony at the rate of $2,500 per month until her death or remarriage . . . Judge McHugh ruled that the letter was inadmissible because it was an offer of compromise or settlement. The Court of Appeals agreed with Judge McHugh’s ruling. We disagree.
North Carolina follows the rule that an offer of compromise, as such, is never admissible as an admission of the party making it. See Mahaffey v. Sodero, 38 N.C. App. 349, 247 S.E. 2d 772 (1978); 2 Stansbury’s § 180.
The reason for the rule excluding offers of compromise as evidence of liability is one of sound public policy encouraging the settlement of disputes out of court. In addition, although a consciousness of liability may be inferred from such an offer, an offer of compromise is also consistent with the desire of an offeror to buy his peace. 2 Stansbury’s § 180. However, the fact that evidence is incompetent for one purpose will not affect its admissibility for other proper purposes. Relevant evidence will be admitted if competent for any purpose. 1 Stansbury’s § 79; McCormick on Evidence § 59 (2nd Ed. 1972).
The letter of 18 November 1976 is obviously inadmissible as proof of plaintiff’s liability to pay defendant alimony. The issue of defendant’s entitlement to alimony was determined in the consent order and is res judicata. Further, defendant’s entitlement is not in dispute. The question at bar is the modifiability of the consent order requiring plaintiff to pay alimony. Modifiability of the consent order depends on whether the order was an integral part of the entire property settlement.
We hold that the letter of 18 November 1976 is admissible as evidence of the reciprocity of the consent judgment and property settlement, an issue separate and independent from that of plaintiff’s liability to pay alimony. We caution, however, that the letter is not in itself proof of defendant’s contention. Defendant has the burden of showing by a preponderance of the evidence that the provisions of the consent order and property settlement were inseparable. White v. White, supra.
*187We hold that this case must be remanded for a hearing on the issue of whether the provision for alimony was an integral part of the parties’ property settlement.
II.
We next address the question whether there has been a change in circumstances sufficient to warrant modification of the alimony decree. Addressing this question becomes necessary in the event it is determined that the consent order was not an integral part of the parties’ property settlement. On this point we agree with the Court of Appeals.
As a general rule, the changed circumstances necessary for modification of an alimony order must relate to the financial needs of the dependent spouse or the supporting spouse’s ability to pay. See Britt v. Britt, 49 N.C. App. 463, 271 S.E. 2d 921 (1980); Stallings v. Stallings, 36 N.C. App. 643, 244 S.E. 2d 494, cert. denied, 295 N.C. 648, 248 S.E. 2d 249 (1978). Our primary concern on this appeal is the change in financial needs of the defendant as a dependent spouse.
To determine whether a change of circumstances under G.S. 50-16.9 has occurred, it is necessary to refer to the circumstances or factors used in the original determination of the amount of alimony awarded under G.S. 50-16.5. That statute requires consideration of the estates, earnings, earning capacity, condition, accustomed standard of living of the parties and other facts of the particular case in setting the amount of alimony.
Defendant argues that there is a distinction between G.S. 50-16.9 and G.S. 50-16.5 and that the above interpretation allows the trial court to retry the issues tried at the original hearing. This argument is not valid. The statutes codified as G.S. 50-16.1 through G.S. 50-16.10 all deal with the same subject matter, alimony, and are to be construed in pari materia. Williams v. Williams, 299 N.C. 174, 261 S.E. 2d 849 (1980). So construed, the change in circumstances in G.S. 50-16.9 logically refers to those circumstances set forth in G.S. 50-16.5. Plaintiff’s status as the supporting spouse, defendant’s status as the dependent spouse and her entitlement tp alimony were permanently adjudicated by the original order.
*188The uncontested facts in this case show that when the consent order of 6 December 1976 was entered, defendant’s expenses exceeded her income of less than $9,000. Her net worth at that time was approximately $1.1 million. After the sale of her Northwestern stock and reinvestment of the proceeds, her non-alimony income in 1979 exceeded $54,000.00. Defendant’s expenses that year were $32,400.00 leaving her more than $21,000 in income over expenses exclusive of any alimony. We agree with the Court of Appeals that under these facts, there has been a change of circumstances as a matter of law.
Defendant’s change in her financial holdings from a passive investment in Northwestern to investments actively producing income was voluntary. When she did this, defendant changed her need for maintenance and support. Defendant is not depleting her estate to meet her living expenses. Her income derives almost exclusively from interest earned on her investments. Defendant herself admitted that “my separate income is well over what I spend for living expenses. No, that was not true on December 6, 1976.”
In Williams v. Williams, supra, we said:
Nothing in this decision is designed to allow plaintiff to increase her wealth at the expense of defendant. Under the guidelines established, plaintiff would be required to continue in expending all of her annual income if she desires to maintain her present standard of living. Should the wife’s capital assets increase in value, through inflation, prudent investment or otherwise, and results in an increase in her income, defendant would, of course, be entitled to petition the court for modification of the alimony order under G.S. 50-16.1.
299 N.C. at 184. See also Sayland v. Sayland, 267 N.C. 378, 148 S.E. 2d 218 (1966).
If it is determined that the consent order was not an integral part of the property settlement, plaintiff is entitled to a modification of the order requiring him to pay $2,500.00 per month in alimony. We emphasize, however, that defendant can rely on the original finding of entitlement in the consent order.
*189III.
Defendant lastly contends that she is entitled to attorney fees incurred in resisting plaintiffs motion in the cause. To be entitled to attorney fees it must be shown that they were necessary to enable the dependent spouse, as litigant on substantially even terms by making it possible for her to employ counsel. Williams v. Williams, supra. The dependent spouse must be unable to defray the necessary expenses of the litigation. Hudson v. Hudson, 299 N.C. 465, 263 S.E. 2d 719 (1980). Considering defendant’s current financial status we find her argument without merit. She is clearly able to defray the expenses of the litigation. An award of attorney fees in this case is not necessary to enable defendant as litigant to meet plaintiff as litigant on substantially even terms.
IV.
This cause is remanded to the Court of Appeals. That court will vacate the order appealed from and will remand the cause to the trial court (1) for further hearing and determination of the issue of whether the consent order was an integral part of the parties’ property settlement; (2) for specific findings relative to defendant’s costs in maintaining her accustomed standard of living as ordered by the Court of Appeals; and (3) for entry of a new order consistent with this opinion.
Affirmed in part; reversed in part and remanded.
. It will be noted that the consent order was entered on 6 December 1976.