Ah, it's an age old problem. The problem with keys is that they're so easy to make loud and 'big' without much effort that they can always drown out the rest of the band, never mind just the bass, and because they can be employed with such versatility, keys players who love the sound of their own playing can feel encouraged to play constantly, over everything.
Years ago when I worked at a hotel, we'd regularly have bands coming in to play functions and weddings. One band always used the set up worth their guy on a Nord Lead II (a keyboard I never really liked the sound of). He was invariably devastatingly loud and piercing to the detriment of the rest of the band. I always did wonder if they knew how much of the FOH sound was occupied by that noise.
In this instance, I think some diplomatic conversation would be in order. A keys player can play a bass part but they can never make it sound like a bass guitar even if they have a good patch, in the same way as a drum machine doesn't bring the music to life like an actual drummer would. If the band are happy enough with stiff-sounding keyboard basslines, your daughter might be stuffed but if they band have any sense they'll recognise and address the issue.