For Pi Day, a post brought to you by the number three: A New York judge has granted shared custody to three people who had been raising a child together in a polyamorous triad—and relied on the earlier case of a two-mom couple in in his ruling.

Two of the parents, Dawn and Michael Marano, were legally married when they became romantically involved with their neighbor, Audria Garcia. Dawn was infertile, so the three agreed that Michael and Audria would become biological parents to a child all three would raise, reports the New York Post. Later, Dawn and Audria decided to continue their relationship without Michael. Michael sued for custody of the child; Dawn sued for divorce from Michael. Dawn then petitioned for custody, shared among the three of them, which the judge granted (although Michael says he will appeal).

In his March 8 decision, Suffolk County Supreme Court Justice H. Patrick Leis III wrote that his ruling relied on the New York Court of Appeals decision last August, which said that a person not related to a child by biology or adoption may still be considered a parent if they and the other parent agreed to have and raise the child together—even if the two adults are not married. He explained, “Tri-custody is the logical evolution of the Court of Appeals decision in Brooke S.B., and the passage of the Marriage Equality Act and DRL [Domestic Relations Law] §10-a which permits same-sex couples to marry in New York.”

Same-sex-headed families are thus paving the way for a greater recognition of other family types. But recognizing more than two parents, while still rare, isn’t a completely new idea. See, for example, the 2010 Boston Globe article “Johnny has Two Mommies – and Four Dads,” which observed that “A few family-law scholars have begun to argue that there is nothing special about the number two — if three or four or five adults have a parental relationship with a child, the law should recognize them all as parents.”

And there are plenty of examples of the law recognizing three or more parents:

  • LGBTQ family law expert Nancy Polikoff, at her blog, has noted several cases from the 1980s. NPR in 2014 reported that Louisiana, Delaware, Pennsylvania, D.C., Oregon, Washington, Massachusetts and Alaska have all recognized three-parent families (and profiled one family that has benefited). They seem to have missed a February 2013 case in which a Florida judge allowed three people—two lesbian moms and the man they asked to be their sperm donor—to be listed on the birth certificate of their toddler.
  • In Canada, an Ontario court ruled back in 2007 that a child can have three legal parents: the bio mom and dad and the bio mom’s partner.
  • On the legislative side, British Columbia, Canada enacted a law in 2013 allowing for three parents, but also recognizing that in most cases, sperm donors are not parents: “There is an exception to the general rule that a donor is not a parent if the donor and the people who would be the child’s parents (i.e., birth mother and her partner) agree before the child’s conception that all three will be the parents of the resulting child.”
  • California enacted a similar law the same year. Polikoff noted that while same-sex parents would likely use the law to give rights (if desired) to known donors, many families with straight parents would also benefit:

This statutory authorization, however, is most likely to impact heterosexuals, given how much divorce and remarriage there is. The provision will mean that if both the custodial and the noncustodial parent agree, then the custodial parent’s new husband will be able to adopt the child without terminating the rights of the noncustodial parent.

I’m delighted by all this, even though I’m personally perfectly happy with my one spouse and our decision to use an anonymous sperm donor. A rising tide lifts all boats, LGBTQ and otherwise. In the end, if recognizing more than two parents helps children maintain ties and stability with loving, responsible adults who are raising them, it’s a good thing. As Judge Leis wrote about J.M., the boy in the most recent case, an in-person interview with the boy left “no doubt that J.M. considers both plaintiff and Audria to be equal ‘mommies’ and that he would be devastated if he were not able to see plaintiff…. J.M. also clearly shows that he enjoys his present living situation and would not want it altered in any way.”

And yes, I know that pi is three and a bit. Think of it as three parents and their child, and it works. Love, like pi, makes things go round.