I understand is "madre de crianza temporera" Entiendo es madre de crianza temporera.Madre adoptiva is adoptive mom and I think it is when is forever. mildred&john
Remember that here in US there's a lot of Spanish teachers who's Spanish is not there tongue/native language and doesn't know some specific words of the language. My native tongue is Spanish and my second language is English. I'm sure of the meaning that I gave you.
I noticed one of the original Spanish documents from our agency referred to her as "la madre substituta." I have a feeling there are many "acceptable" translations. Lisa