The IRS understands the situation and is aware that providers don't break things up. As long as you enter the correct amount on each return, you are fine.
The IRS does have forms you can file, but those are really meant for passing income to another person. You could do a nominee for the dividends, General Instructions for Certain Information Returns. It is not expected in your position but if it makes you feel better, you could issue a 1099-DIV from the individual to the estate.