Help with feeding

So baby wakes up (when she actually naps which isn’t much) and I try to feed her her whole bottle right then when she gets up but lately she’ll take like 1/2 oz and be over it . She then doesn’t sleep and will get fussy about an hour later and want the bottle idk what to do to get her consistently finishing her bottles

Doesn’t help that gpa is in town watching her with us this weekend and is letting her wake up at night for 1oz just enough to put her back to sleep because “whatever keeps her happy”