Filing a 1040X to include K-1

I may have already posted this question so apologies if I did.

 

I've already filed my 1040 but I may have a  capital loss from the sale of a home that was in a Trust.  If I do indeed need to file the K-1 in the 1040X what is the simplest way to accomplish this?

 

Also, it's my understanding that adding the K-1 will automatically populate (in this case a loss) schedule D and I'm limited to $3,000/year to have capital losses offset capital gains.

 

Finally, I read that the K-1 can only be filed once the Trust is closed.  Is this true?

 

Thank you for the help!