Two Login's for One Account

There are a ton of separated parents(also grandparents) that have to pay on one account. If there was a way that each parent could have a login ID & password for the same child's account, so that they could pay without having each others payment information. A lot of the parents don't want to share their passwords with the other parent, because their payment information is saved on the account. I also have some grandparents that like to pay sometimes & they would like their own login ID & we could choose what is shared on their parent portal.