It would be great to have an additional option with the vault where you and your spouse could have separate doors or have your balances separate or something.
Maybe an additional upgrade to split the vault, but still not have more than the maximum combined?
Would make things a lot simpler for people who share the vault and have to keep up with who has what balance.
I'd pay 25m for that. Maybe add 10-20 max happy as an additional boost?