I have a question in regards to doing punnett squares. I know the basics of how to set them up with single gene animals. I can also set them up when both animals are double gened. I am just curious how you would set up a square for breeding a single gene morp to a double gene morph. Do you have to add extra filler letters to the single gene? Just something I would find convenient to know instead of using the calculators online.

Brennan