I have a wonderful suggestion why not name her middle name after her own beautiful Mother's middle name, so Leah if you have a middle name would it go with Isabelle

I understand your 1st name won't work as the initials would be ILL !!!

(At times i wish i did the same for my DD but instead named her middle name after my sister who sadly took it as sympathy and not as the most loving gift i could give her ... It ripped our relationship apart as she asked we change it by deed poll when DD was 9mths old, my only child, of course i didn't as that was her birth name & that was the way it was going to stay ... my DD will always know she was named after a sister i loved so dearly)