Searchbox for content of repeating group

on this app
patients (user) can create many consultations
so each consultation has a creator.
so I have a repeating group that is a list of consultations
I want a search box to search for a consultation creator’s name
I found out that since the “created by” field data type is user, it cannot the searchbox value can’t search through it, it can only search the text fields in consultations but not a user’s name.
I need help with that