can my daughter have her own number to add to family sharing

You misunderstand the basis of Family Sharing. Apple IDs are the identifier of family members. Your daughter will need and, if she has her own iPhone, probably already has an Apple ID .

Phone numbers are associated to Apple IDs by the phone signing in with an Apple ID. From this, the number can be used with Messages and FaceTime on that Apple ID.

Read What is Family Sharing? for Apple's explanation of the service and the link on that page to set it up.

Are asking to share one phone? That would be no. iPhones are not a multi user devices. If she has her own iPhone she can be added to a family plan.