DD gets mostly BM but we also supplement with formula. She has no problem switching around from nursing, bottled BM, powdered formula, or RTF formula. We keep RTF 6oz Enfamil bottles in the diaper bag all the time just in case. You shouldn't have a problem unless she is just extra particular.
Re: temorarily using RTF formula in place of powdered?
DD gets mostly BM but we also supplement with formula. She has no problem switching around from nursing, bottled BM, powdered formula, or RTF formula. We keep RTF 6oz Enfamil bottles in the diaper bag all the time just in case. You shouldn't have a problem unless she is just extra particular.