You are supposed to be working in the Regular file under restrictions, not "in the accountant's copy." If you are working in the Accountant's Copy, you are in the wrong file. That's the one to Send, not to use.
You should be able to add Jobs and other info that is Later than your Divided date. What you cannot do is add historically dated activity to that file, such as Add Job with a backdated Estimate. Or, Add Job and Invoice for a prepayment dated in Dec.