I agree with your DH that she is doing what a member of a family does, but i also agree with you that this is a cause for celebration and recognition

Perhaps you could get her a beautiful book, with blank pages, and write in the front what you have put here, how wonderful she is, what a help, what a support, how much you love her. A diary for her to write in, or maybe even a book for you to write to one another in? Or if she's not a diary type then a beautiful, expensive card, the sort one would send to an adult girlfriend. The words will last longer than anything you buy her (except maybe jewelry) and she'll be able to read them back in good times and bad and know how loved and appreciated she was. My mum sent me several cards like this and since her death in 2005 i have so appreciated being able to read back how it was with us when she was here and it's even helping to shape the way i treat DD.

Anyway, you two should be very proud too, she didn't grow into such a responsible helpful caring girl without a pretty special mama and dada modelling those personal attributes themselves.

Bx