Gay couples can form a family and become parents through surrogacy. In the process, they may choose to give both a semen sample to fertilize a donor's eggs. Thus, one part of the eggs would be fertilized with the sperm of one and the other with the sperm of the other.
One or two embryos would be selected from all the embryos obtained, both from one embryo and from the other, depending on their quality and whether or not they wish to have a multiple pregnancy. The selected embryos are transferred to the surrogate to see if a pregnancy happens.