"backing out" 1099-DIV for nominee

My wife died in May. I have a 1099 from her brokerage account that's in the name and tax ID of her trust. The broker ceased operations in September. So the trust is responsible for the dividends paid May-September, while the dividends January-May actually belong to our joint 1040 tax return. I know how to file a 1099-DIV in which the trust pays those January-May dividends to my SSN for our joint account. But how do I reduce the 1099-DIV I got from the broker, so as to subtract those January-May dividends from the January-September toal shown on the brokerage 1099-DIV? If I simply over-ride the figures, I can't e-file, right? And in any event the IRS knows perfectly well what the broker says it sent the trust.

 Perhaps I should create TWO new 1099-DIVs, one in which the trust pays me and the other in which the trust pays itself?

Thanks for guidance!