Can I mix formula and breatmilk?

leah2b

I am at the 7 month mark and have been working FT since 5.  Recently my supply has tanked considerably, so much so that I am only able to get about 12 ounces with 5 pumps a day.  My DD is a big baby for her age and needs more fluid, even though she is taking some solids now,  I have no freezer stash because she was a bottle refuser for a while and  went through a ton of milk trying to get her back on the bottle in preparation for daycare.  I really do not want to fully wean at this point  and neither does she.  I just need a little extra for daycare.

Can I mix a little formula in the bottle with the breastmilk?