For gay couples, it’s possible for both intended fathers to be biologically related to the child through a process known as multiple fertilizations. In this approach, each father’s sperm is used to fertilize separate donor eggs. The fertilized eggs are then implanted into the surrogate, with the hope that both will develop into pregnancies. This way, each father could have a child that shares their genetics.
Alternatively, if you want a child who is related to both parents but can only use the sperm from one, you could work with a close female relative of the non-biological father as an egg donor. That way, the child would be genetically linked to both of you. For example, a sister or cousin of one partner could donate her egg, which is then fertilized by the sperm of the other partner. This creates a biological link to both intended parents.