It helps a lot that there are people with the name and it’s pronounced the same way!
I also really love your suggestion of [name_u]Marin[/name_u] [name_f]Estelle[/name_f]! [name_f]My[/name_f] great grandmas middle name, she was actually the mother of my grandma [name_f]Mary[/name_f], was [name_f]Estelle[/name_f]. That might be cool and extra special for my grandma too! Thank you!!
I don’t typically love “y” names, but I think [name_f]Maryn[/name_f] is sweet with the tie to [name_f]Mary[/name_f]! And, I intuitively pronounce this spelling more like [name_f]Maren[/name_f]. I don’t dislike [name_u]Marin[/name_u] but just note that people may say “Mah-RIN” in parts of the US because that’s how it’s pronounced in the San [name_m]Francisco[/name_m] area (Marin County). This wouldn’t be a deal breaker for me, though, as we live on the opposite coast — plus, it’s an easy correction!