If I already had apple music on family by adding Apple One it just automatically switches us all to Apple one?

See step 4 in the 'How to get Apple One' section. of:

Bundle Apple subscriptions with Apple One - Apple Support'

"If you already subscribe to Apple Music, Apple News+, Apple Arcade, or Apple TV+, you don't need to cancel those subscriptions. They will automatically be canceled when you're billed for Apple One."

Just make sure you get the Apple One Family plan.