Everyone has an opinion. No opinion is the same.
My opinion – drop the prefixes when it comes to titles.
Mother is mother, mom, mama or whatever is the norm in your culture. Same with Father. Yes, it really is that simple. How you word the sentence explains the relationship of the title holder.
If someone says “Tom went to see his mother today” – it is pretty clear-cut and dried that the mother referred to in the sentence is Tom’s mother. If Tom is an adoptee and the author is Tom’s mother through adoption then the obvious conclusion is that Tom saw his mother who gave birth to him.
Why would you need or want to add a prefix like bio, birth, first, natural or conversely if the author was Tom’s mother who gave birth to him, adoptive or adopter prior to the title.
And no, the adoptee is not confused by this. In my opinion adding prefixes makes us even more different from bios. Why can’t we have two mothers and two fathers?
More to the point, my can’t people just put away their insecurities and their needing to be the top dog at the party? Why?
Terms like bio, birth, first, natural once a mother and father have signed that piece of paper relinquishing their rights go from the best, strongest, bravest, most saintly individuals on this planet right down to the dregs of society. They fall from grace so fast you cannot even keep up. They are no longer considered family and must be boxed in, denigrated with prefix to their rightful titles, firm boundaries laid, all to make the adoptive family the top pack in the hierarchy of titles.
Enough, lets just go back to being humans who want what is best for all. Trust me, it does not confuse the adoptee.