FMIL has mentioned in the past how we are going to word their names. She assumes the groom's parents will be included on the invitation. I still have to check and see what my parents think, but assuming it's ok with them we will do the "son of" thing to include them. That aside, both of our parents are divorced. Here is how it looks:
Me: Parents divorced, mom never remarried but dad remarried. He remarried to mom's old best friend, and though there's hurt feelings, yes I do consider her a stepmom that is hosting equally with my dad. Mom never re-changed her last name though! For that line would it be Mr. and Mrs. Dad last name and Ms. Mom same last name?
...invite you to.... marriage of Me last name ... to FI last name... son of
FI: Parents divorced; both have re-married and re-divorced. Both have SOs right now but are not married. His mom did change her name back... so: son of .... Mr. Dad last name and Ms. Mom her last name?
Hope that's not too confusing. Thanks!