ROPA stands for Reception of Oocytes from PArtner
Basically it consists on performing an In Vitro Fertilization involving both women of the couple and one anonymous semen donor.
One of the partners provides the oocyte that will be inseminated with anonymous donor sperm . The embryo generated will be transferred into the uterus of her female’s partner who will be carrying the pregnancy.
A few years ago this technique was not permitted as it was considered a gamete donation and the Law on Human Assisted Reproduction clearly establishes that donations must be anonymous. However on 2005 the civil code was modified and homosexual marriages have the same rights as heterosexual ones. Thus, R.O.P.A. cannot be considered as a donation given that one partner of the couple is sharing her gametes with the other partner, as it happens in a heterosexual marriage where the husband share his sperm with his wife.
Therefore, both women have the same rights and obligations on the baby with no need for one of them to adopt him, as it happened before.