*613OPINION OF THE COURT
Kupferman, J.The petitioner-appellant in 1977 moved in the Family Court for an order of filiation, declaring the respondent Edward L. to be the natural father of her son who bore his name, Edward L., Jr. On the consent of the parties, an order of filiation was entered into, with provision for support for the son until he reaches the age of 21 years. Obviously, the petitioner from the very beginning believed the respondent to be the father of her child, and he readily accepted the responsibility. Clearly, he is entitled to all the rights of a natural father. (Caban v Mohammed, 441 US 380; see Silk, Adoptions—Making the Unwed Father Equal, NYLJ, May 7, 1979, p 1, col 2.)
Some 10 months after the entry of the order of filiation, the petitioner mother moved for an order vacating and setting it aside and granting a new hearing upon alleged newly discovered evidence. Together with the petition, which has an affidavit by counsel only and none by petitioner herself,* there was a letter from a physician stating that it was her understanding that Mr. L.’s blood type is O positive, and that the mother and the child have blood type AB negative, in which case parentage for Mr. L. is excluded. (See Schatkin, 1 Disputed Paternity Proceedings [4th ed], §§ 5.05, 5.10.)
The dissent would remand for a hearing on that question, but to what avail? The motive for the petitioner mother’s subsequent change of heart is undoubtedly, as set forth in the dissent, her difficulties with the respondent and his having initiated a proceeding under section 651 of the Family Court Act, seeking custody of the child. (See Braiman v Braiman, 44 NY2d 584, 589; see, also, "The Woman Pays”, The Bronx Bar Advocate, vol 25, No. 5 [Nov.-Dec., 1978], p 115; cf. Orr v Orr, 440 US 268.)
At common law, there was a presumption of legitimacy in marriage, even though the wife was adulterous, given the cohabitation of the parties in conjugal relation at the time of conception. (Fisch, New York Evidence [2d ed], § 1129; Richardson, Evidence [10th ed], § 59.) The common-law rule has been abolished in New York State (Family Ct Act, § 531), *614allowing a husband to attempt to establish his nonpaternity. One way to help establish exclusion of a possible father is the blood grouping test. Usually, the purpose of the test is to aid the putative father in establishing his blamelessness. In fact, sections 418 and 532 of the Family Court Act provide for a blood test "on motion of the respondent”.
Shakespeare confirmed that "it is a wise Father that knows his own child” (The Merchant of Venice, act 2, scene 2). Unlike the mother, this respondent submits his own affidavit to the effect that the parties were living together at the time of conception, and in this case the father has assumed his responsibility, and the mother, when it suited her purpose, chose to foist responsibility upon him. The child benefits by the support provided, and it is the interest of the child with which we are most concerned. (Matter of Orlando F., 40 NY2d 103.)
With respect to the best interest of the child, it has been recently stated by Judge Cooke (now Chief Judge) that there is a "heavy burden of constitutional magnitude on one who would terminate the rights of a natural parent” (Matter of Corey L v Martin L, 45 NY2d 383, 386-387). Surely, such postulate is reinforced where, as here, there is a determination concurred in by both parties to the proceedings and by the court, resulting in a judgment. If there is additional evidence, and we do not have anything more than speculation, it is not newly discovered but rather recently sought.
The petitioner mother having sought the jurisdiction of the Family Court to establish paternity and having obtained the benefit of the judgment so secured, should now be estopped from seeking to have the court annul the judgment. (Matter of Montelone v Antia, 60 AD2d 603; cf. Psaroudis v Psaroudis, 27 NY2d 527.) The more so, when she offers no alternative possibility but merely suggests the respondent’s possible exclusion to the detriment of the child’s parentage. The child should not be kept in limbo. (Matter of Sanjivini K., 40 NY2d 1025, 1026-1027.)
The order of the Family Court, New York County (Thurston, J.), entered on or about December 20, 1978, should be affirmed, without costs.
On a matter such as this, there should be an affidavit by the party involved and not merely by counsel. (Capelin Assoc. v Globe Mfg. Corp., 34 NY2d 338, 342; Pathmark Graphics v J. M. Fields, Inc., 53 AD2d 531, mot to dismiss app granted 40 NY2d 1093.)