My opinion

1. She does NOT have to file a 1099-DIV for the estate. 

Usually clients get a complete statement from the Accounts, that has detail pages behind the summary 1099, She may be able to (hopefully) get those for you so you can figure out the apportionments.

Enter the entire amount on the individual's 1099 on the schedule B input, and double click on the payer name and you can open a schedule B worksheet - Line D Check nominee and the amount of dividends belonging to the estate, and that will get subtracted on the individual schedule B, I believe that only works for Ordinary Dividends. Everything else (Qualified, Capital Gains etc.) I don't think you can get it automatically and probably just have to enter the correct amount. (If the difference is significant I might attach a schedule)

Have you considered if the overall tax difference is significant between doing it correctly and just reporting the 1099's on the Individual return? If not significant, I might just blow it off and do it that way, The estate will be writing the check to pay any tax either way right?

Sometimes you can justify to yourself that if the tax gets paid who's going to ask any questions...Again depends on the significance. If were talking a few $100 of Dividends I might go the easy way, If its $50k of dividends my answer might be different.

Have Fun!