with whom CARPENETI, Justice, joins, concurring in part and dissenting in part.
The first part of this separate opinion argues that the commentary to Civil Rule 90.3 should not be construed like a rule or regulation. This point does not conflict with the majority opinion. The second part takes the position that the good cause evidentiary hearing on remand should encompass Bill's defense to CSED's motion to increase child support and Bill's cross-motion to decrease child support. In so far as the majority opinion excludes the cross-motion from the evidentiary hearing, I dissent.
L.
CSED argued in this case that as a matter of law an obligor's support of stepchildren, and the needs of stepchildren, can not serve as a basis for a court-ordered variance from the formula provided in Civil Rule 90.8(a) for calculation of child support. It founded this argument not on the rule, which provides without limitation that support may be varied for good cause on a showing by clear and convincing evidence that manifest injustice would otherwise result, but on the commentary, specifically part VL.B.2, captioned "Subsequent Children" which provides:
A parent with a support obligation may have other children living with him or her who were born or adopted after the support obligation arose. The existence of such "subsequent" children, even if the obligor has a legal obligation to support these children, will not generally constitute good cause to vary the guidelines. However, the cireumstances of a particular case involving subsequent children might constitute unusual cireumstances justifying variation of support. The court should reduce child support if the failure to do so would cause substantial hardship to the "subsequent" children.
In addition, the interests of the subsequent family may be taken into account as a defense to a modification action where an obligor proves he or she has taken a see-ond job or otherwise increased his or her income specifically to better provide for a subsequent family. This defense to an upward modification action should not be allowed to the extent that the prior support was set at a lower amount prior to the adoption of this rule, or to the extent that the obligor's increase in income is limited to ordinary salary increases.
In considering whether substantial hardship to "subsequent" children exists, or whether the existence of a subsequent family should defeat a motion to increase child support, the court should consider the income, including the potential income, of both parents of the "subsequent" children.
(Emphasis placed on language discussed below.)
Focusing on the "born or adopted after" language in the first paragraph, CSED argues that stepchildren can not be considered "subsequent children" within the terms of the commentary and their needs in no circumstances can amount to good cause for varying a formula-based award. But other language in the commentary seems inconsistent with this reading. The "even if" language of the second sentence of the first paragraph tells us that "subsequent children" may include children for whom the obligor has no legal support obligation. Stepchildren are the most typical members of this *746class. And the second paragraph permits the needs of the "subsequent family" to be taken into account in certain cireumstances. It is hard to think that this includes the new spouse and in-laws, but excludes stepchildren.
CSED does not mention the "even if" language. But CSED explains the second paragraph of the commentary by arguing that it can only be made consistent with the first paragraph if "the subsequent family" is construed to exclude stepchildren. Today's opinion rejects this argument, seeing "no reason to discourage a parent from taking on additional work for the specific purpose of caring for a new family" even where, as here, the children in the new family are stepchildren. Slip Op. at 748 n. 17. This ds a practical, common sense conclusion and I agree with it. This conclusion also implicitly rejects one premise of CSED's argument which is that the commentary is to be construed like a rule or regulation.
The commentary is the product of the Child Support Guidelines Committee. It is published for "informational purposes to assist users of Rule 90.3" but it has "not been adopted or approved by the Supreme Court."1 Although we have frequently relied on the commentary for guidance, we have also rejected it in some respects and permitted support calculations contrary to its methods.2 It is a mistake to parse the language of the commentary as if it were a rule or a regulation or to apply the rules of statutory construction to it. Unlike rules or regulations, the commentary has not been written with an eye toward precise distinctions. For these reasons, it is ultimately unproductive to strive to determine the meaning of Rule 90.3 by attempting to resolve inconsistencies or ambiguities in the commentary.
IL.
The majority's conclusion that Bill may have a defense to CSED's efforts to increase his child support necessarily means that under appropriate cireumstances good cause for varying formula child support may be based on an obligor's assumed responsibilities to stepchildren. But the majority limits the permissible seope of the variance in this case to a defense to the increase sought by CSED. Bill sought, in addition, a decrease in his current obligation. The majority concludes that no evidentiary hearing is needed on this claim because "Bill did not allege the special cireumstances that would entitle him to a support reduction." Slip Op. at 740. I disagree with this conclusion.
Trial courts should grant evidentiary hearings on support modification motions where the movant alleges facts that, taken as true, could warrant modification. This is what we mean when we say that the movant has established a prima facie case.3
Here the majority opinion says that Bill has not met this standard because "he merely asserted in his affidavit that 'a reduction in my support for Valerie would help me care for my new family'" Slip Op. at 744. But that is merely one of several conclusory allegations made by Bill in his moving papers. He also claimed that "extraordinary expenses incurred in caring" for his stepchildren made this case "one that falls squarely within the unusual circumstances of Civil Rule 90.3, as explained in the commentary." He also stated, "strict application of the rule would cause an undue hardship on defendant's subsequent family, and thus unusual cireumstances exist which warrants a considerable reduction in defendant's child support obligation."
These are, of course, merely conclusory allegations and I mention them only because the majority opinion relies on one modestly stated conclusory allegation made by Bill to justify denying him a hearing. But concluso-ry allegations can not make a prima facie case. Instead, facts must be alleged which, if true, could warrant modification.4 I believe Bill has met this standard.
*747Bill has alleged (1) in some detail that his stepchildren have substantial and expensive medical and educational needs;5 (2) that he is the sole means of support of the stepehil-dren6; and (8) that he has taken on additional work to increase his income in order to support the stepchildren but that the increase in his income is not sufficient to provide for their extraordinary needs.7 Thus Bill presents underlying facts which if accepted as true could support a discretionary determination by the trial court that unusual cireumstances exist requiring a variance in formula-mandated child support. For these reasons I believe that the inquiry on remand as to whether there is good cause to deviate from formula child support should pertain both to CSED's motion to increase support and Bill's cross-motion to decrease support.
. Alaska R.Civ.P. 90.3 commentary LA.
. See Eagley v. Eagley, 849 P.2d 777 (Alaska 1993); Bunn v. House, 934 P.2d 753 (Alaska 1997), and cases there cited.
. See Acevedo v. Burley, 944 P.2d 473, 475 (Alaska 1997); see also Morino v. Swayman, 970 P.2d 426, 428 (Alaska 1999).
. See Morino, 970 P.2d at 428.
. In his affidavit, Bill states that his two youngest stepchildren suffer from significant medical conditions, including severe asthma, allergies, heart blockage, ADHD, ear blockages, and dental problems. Bill also alleges that both young stepchildren require special education, and that he and his wife must pay part of the cost of this as part of their home schooling arrangement. This affidavit was explicitly filed in support of both Bill's cross-motion for downward modification of support and his opposition to CSED's motion to increase support: "Both the opposition and cross-motion are supported by the memorandum of points and authorities filed herewith and the affidavit annexed hereto." Opposition to State's Motion to Modify Child Support and Cross Motion for Modification of Child Custody and for Order Requiring Plaintiff to Pay Child Support.
. Affidavit, paragraphs 5 and 8.
. Affidavit, paragraph 8.