My (limited) understanding is that if you have to attach the court appointment letter (in VA it's called a "Letter of Qualification") then you have to paper file.  If the timing is such that, say TP dies on 1/15/19, you paper file the 2018 tax return with the letter attached, then you can efile the 2019 return and check the box saying that the information is already on file (although about half the time, the IRS will reject the efile because it somehow has a flag for TP deceased and is trying to prevent a fraudulent return).

Not sure why we can't just mail in the document with an 8453 but I haven't figured out how to do that.  Let me know if you figure it out, I have one pending now that will need to be mailed in.

Rick