Change Organizer & Previous Shared Purchases

We want to change organizer in our family. I understand that everyone needs to leave the family. All being 13+ yo, they would be able to remove themselves. At that point, it seems I would start a new family and send invites to the family members, correct? By doing this, I would be the Organizer?

The second part of the question is, what happens to the purchases made by family members while they belonged to the old family? Do they become shared, again, in the new family? Our children have been very smart in making their purchases with gift cards, etc.

I have read the article on stop sharing (Leave Family Sharing - Apple Support), but it leaves out what happens when you join a new family.

All help is GREATLY appreciated.