One More Wrinkle on Amending Contracts
Unfortunately, although simply amending the contract may seem like a solution in such circumstances, it isn't because the editors obviously don't look at what you do send. If they did, you'd be back in trouble because they'd resent that you actually changed something without asking.
Also, ever get a signed agreement with the changes back from these editors? If not, the door open, in case of a legal conflict, for the magazine to argue that the original terms were the ones that governed the relationship and that you wouldn't have proceeded without getting a countersigned changed document. To win you'd have to go to court, but the results would be uncertain, and that means you'd have already lost considering the costs of taking legal action.