I am sorry for your loss.
In short, you need to file three returns (two trust 1041s and one estate 1041) assuming the trusts and estate exceed the income threshold for filing.
There is such a thing as a Section 645 election where QRTs are treated as part of the estate and then, if made, a trust is treated as part of the estate and one return is file (for the estate). However, the procedure is rather complex and outside the DIY arena.
See https://www.thetaxadviser.com/issues/2024/may/the-sec-645-election-to-treat-a-trust-as-part-of-the-e...
