My mother is taking care of my father who is home bound and needs 24 hour care which she was undertaking.

 But she is of poor health as well. My mother of course is POA for my father. My sister is a secondary POA for my father. If my mother is hospitalized can my sister exercise her POA to get my father the care possibly temporary admission to a nursing home if he would need in my mothers absence? My sister cannot take care of him on here own and I live too far away.