You can file a 1065 as a partnership if you want. There's nothing that says you can't, or keeping you from doing so for the 2021 tax season. Overall, you may find it a better way do keep things split as they should be.
Just be aware that a partnership return filing deadline is March 15th. That's a full month before the individual income tax filing deadline.
So for example could one person claim 70% of the income yet only 30% of the expense, and vise verse ?
No. That would be seen as one of the partners trying to avoid a higher tax bracket, by claiming 70% of the expenses, while receiving 30% of the income. Especially if that 30% bumped them into the next higher tax bracket. My guess would be that it would probably raise fraud alert flags.
