Some babies, "wait" for their Mommy to get home.
Or have Mommy try a different bottle/nipple.
But yes, baby gets hungry... and thus fussy. They can't hold out all day without intake and feedings has to be on-demand....
Or you can try and feed baby with a medicine dropper.... that is what some babies have to do.
Or she could have nipple confusion. Since drinking from a bottle and nipple is not the same.
I used the "MAM" brand bottles, from Amazon. It is widely used in Europe and is BPA free and has a natural nipple. My son, breastfed, and liked that bottle.
Does baby ever drink from a bottle at all????
Have you told the Mom, that her baby is NOT taking the bottle, at all????
Mom, needs to know....
I babysat a baby once... that had a hard time drinking from bottles, her Mom's pumped milk. Even at home... and the baby got dehydrated.
You NEED to watch out for dehydration in a baby... very important....
Is baby having enough wet diapers for example????? If not, that is not good....
all the best,
Susan