It can get messy and I'm sure there are standard ways of documenting that I don't know about. I always list the mother plant first - this is what an F1 back cross BC would look like.
MM X BC-(MM/LPS-F1) - F1
Remember, every time you add a new variable the seeds will be F1's.
If I cross the MM X LPS F1's to themselves then the off spring would be F2.
