We uncoupled the joint account when D was 18. We still have her name on one of our credit cards incase there is an emergency and she needs to pay for something expensive as her card has a low limit.
My father put my name on his accounts when my mom got sicker. Made the estate stuff more straight forward.
If D opens an account at my bank, even if under her name only, she can access all our special banking perks and the wealth management services.