m0useanswered grow question a year ago I have back crossed autos with each other. The seeds have all been auto so far. Can look up the diary, its Dinafem's Dinamen OG Kush CBD, tasty strain.
but if you want to cross an auto with a photoperiod or fast flower, the resulting seeds will be a mix of photoperiods and fast flowers with a chance of autos if breeding with a fast flower. the auto trait is a recessive so photoperiod traits take over. This is my limited understanding of it.
Good Luck!