The U.S. Supreme Court legalized same-sex marriage here in Colorado and every other state back in 2015. Many individuals assumed that this would make it easier for moms and dads to exercise their parenting rights. Nothing of the sort has happened, though. Many same-sex spouses still find themselves having to go through the adoption process to legalize their parental relationship with their biological kids.
Some same-sex couples are still required to go through the adoption process to gain parental rights to their children. This requirement exists even though the U.S. Supreme Court reaffirmed their position that there's no difference between a heterosexual and a same-sex couples' marriage in 2017.
Children born to married heterosexual couples are automatically assumed to belong to the two married spouses. Lawmakers don't assume the same about same-sex couples, though.
It's not uncommon for a lesbian mother to carry her spouse's fertilized eggs as a gestational carrier. Even still, it's in those instances that the mom who gives birth gets listed on the child's birth certificate.
In this instance, it may be necessary for the mom who donated the egg that's biologically related to the child to establish their parentage. They may be unable to convince their employer to allow their son or daughter to be included in their health insurance if they don't. One of the parents, in this case, may even have to go as far as adopting their child if they want to be included on their birth certificate or exercise their right to child custody.
Establishing paternity is a relatively straightforward process for unmarried males. The concept of same-sex marriage and parentage is still evolving, however, under the law. A same-sex family law attorney can advise you of what Colorado laws say about parents sharing their kids and help you craft an argument for who should retain custody in your case.