"since the agreement didn't specify a breakdown, "
The agreement did specify a breakdown,
your basis in one lot is 19,000 and your basis in the other lot is 21,000.
When marking Box C or F on form 8949, enter the correct basis yourself.
"we took a big loss for selling a $19,000 lot for $40,000,"
you seem to have your gain/loss calculation mixed up.
When marking Box C or F on form 8949, enter the correct proceeds yourself.
@cottagecharm11
