switch to family plan

My wife and I both have Apple Music on our phones. We are on an individual plan since we share a common Apple ID. Currently only 1 of us can play music at a time and we share a common library. I want to with to the family plan so we can have separate libraries and both play music. I am the organizer for Family Sharing. I plan on upgrading our Apple Music to the Family Plan. When I add Apple Music to her Family Sharing, will she start over with a blank library or will she start over with a copy our existing music library?