A piggy-bank with stablecoins in Ethereum using multi-signature wallets?

Hi! I have this particular use case and would like to share it, so people can recommend any solution besides building the solution myself, so here it is:

I want to keep some USDC or BUSD under a multi-sign wallet which requires 2 signatures to spend the funds (2 of 2 signatures), but, I can see a couple of issues with only having 2 parties and needing 2 signatures to perform anything with any funds in that multi-sign, first: death, second: separation of the parties involved and a need to return funds to each party.

Death: if one of the two parties dies during the duration of this trust of funds(?), the remaining party needs to go through and recover the other party's wallet to do anything with the funds, which is an annoyance at best.

Separation: let's say any of the involved parties want to stop putting money into this trust fund (again: is that the name of this thing?) and leave with their corresponding share of the money, but the other party doesn't want to sign anything, which freezes the funds until the dispute is settled and worst-case scenario none of the parties does what the other part asks, and a judge gets involved to resolve the conflict.

Then, some solutions come to mind solving both particular edge-cases at the same time: involving a third party that plays the role of arbitrator, it could be a lawyer who represents both parties... but these cost money, and you need to trust the lawyer to do The Right Thing™.

To me, what comes to mind is a smart contract, is cheaper than a lawyer, and you can write one (if you know what you are doing) to do The Right Thing™, but a smart contract can control 100% of the funds and do whatever N-of-M signatures requests, right? I wonder if a smart contract can be a signer party in a multi-sign wallet, my reasoning for that is that the "N-of-M+smart contract" signers control 100% of the funds, if someone smarter than the person writing the contract want to exploit a bug, the attacker won't get anything of value because he still needs other signers to participate in the "hack" (2 of the 3 signers in this case); thus you get security with the added value that one of the signers can request the smart contract to sign something and the contract will execute under given conditions for an amount of time (a week, two months, etc., time as needed)

Okay, so the question: is there something like this out there in Ethereum that can be used for cheap and with a frontend that won't banish suddenly, or do I need to build it myself?