My parents as grandparents helped my DSister on her return to f/t work, one full day a week, with her last pre school son. Her In Laws had to do one full day also, and her DH, my BiL, cut his hours for a year.
One day was enough for my then seventy something DPs. Could you not offer one consistent day a week Annie221 and specify maybe one child?
This might help your DD2 with childcare costs and also might mean she and her DH have to look elsewhere for more childcare. This would mean it isn’t all on you, with emergencies etc.
Good luck. Guilt is a tricky thing.
Children holidaying during term time.
How does a 'lived experience' differ from an 'experience'?
Cross partyAsylum seekers in UK should have right to work after six months!