You can contract for anything that does not violate public policy (e.g. in my state you can do a separation contract, but you can't contract to divorce; I couldn't contract with someone that they would give up their constitutional rights; let me kill them, etc.). But you should be good about a temporary agreement about how much you guys can each take until there are final orders in your case. But yes, always check with an attorney licensed in your jurisdiction and experienced in the law at issue (but avoid generalists like the plague--jack of all trades; master of none).
