Personally i wouldnt bother with milk at daycare. If u replace her middle of the day boobie feeds with formula its just setting you up for breast refusal when shes not at daycare.

My DD (17 months) has just gone off formula all together, but she stopped the middle of the day milk at about 10 months and was fine with just water.

Anyone feel free to correct me if im wrong.. its just my personal opinion and understanding.