My personal opinion...you are very thoughtful and understanding, but, she is an adult and she will make the adjustment as she sees necessary.
I have Aunt's who I call by name, X-Aunt's who I still call Aunt, and In-law's who were never my In-law's. I probably change that up once in a while, but I don't think that bother's anyone.
The in-law's who are not my in-laws are my X-brother-in-law's parents. I dated his brother in school (I am way beyond my school years) and my daughter (not his daughter) called them Nanny & Pappa. She will always call them Nanny & Pappa and I will always refer to them as such. My husband has never appeared offended. The brother who I dated has an X-girlfriend who had 2 of his children. We are friends and we share the use of the name Nanny & Pappa side by side. They are both aware of the life we had before them.
I know that is not the case for every family, but it works in this case. I would hope she is able to adjust that if it hurts someone's feelings.
So, in response...relax, it will all work out.