the best thing you can do by inbreed, breed the hatchling back with their patty parrent (father/mother)
patty x het patty
so you'll get more percentage (50% patty n 50% het patty)
A high yellow with a murphy patternless will give you Normals/High yellows het for patternless.
Murphy Patternless is a recessive gene, which means the animal will need two copies of the gene (1 from the mother and 1 from the father) to be visible. Your best bet with the two you have now, would be to take a het patternless and breed (when the time comes) to the parent patternless. This would give you 50% normals het patternless 50% Murphy patternless'