In all walkthroughs that I could find I was advised to recruit Grimzel in the dungeon as she is the blind daughter of the druid Grimz that we're trying to revive and would need to have in the team because of his unique fire protection spell. However I couldn't find anywhere any further interaction about Grimzel or any point where she would indeed be needed - even when his father, the druid was revived in the mountains, there was no hint about them meeting again.

...ah OK, I tried and although he doesn't say a word about meeting her daughter, he wouldn't join if she's not in the team, only asks 'Where is my daughter?'. I'll leave it here anyway for anyone having the same question in the future.