This is a brilliant idea. There must be something like this in existence aimed at larger businesses so it's just a case of finding those platforms and testing them for use with smaller groups of people.

For anyone wanting to do something like this, it could be worth contacting their bank and ask if it's possible for an income split from an account set up for the purpose so there isn't a specified amount sent to each personal account but rather any money that arrives in the group account is sent out at a specific part of the month or year to the beneficiary accounts. I know you have said you don't like contracts but if earnings are high enough to justify it, a trust can be set up easily enough and the trustees can be left to split the income (net of tax in many cases) and send it to you. They can also deal with the legal stuff too if you have it as part of the trust deed. (I am a law student and have an interest in trusts and wills that is why I mentioned trusts, it seems quite easy to set one up).

Good luck, I hope you find a great platform that works for you ;-)