you could but it would be.......... well here is the deal you mix pollen now you have no clue what your gonna get, you could polenate seperate branches with difrnt pollens to get difrnt crosses and to get fem seed you need to either use some fancy chemical or stress a fem into producing pollen(balls) then pollenate a fem with the fem pollen
mixing pollen wont make a crossed strain it will just give you seeds that are crossed with whatever pollen made it. you cant pollenate a pollenated plant so if strain A pollenates plant A then pollen b must pollenate a diffrnt part of plant A so it will create a seperate seed than pollen A
its confusing i know, it confused me, but in short mixing pollen together will give you crossed seeds but which are which, you dnt know so put your pollen in a bag put bag over branch to be pollenated and shake it around then mark what cross it is and repeat on a diffrnt branch with difrnt pollen and now you have 2 crossed strains on the same plant
mixing pollen will just give you confusion, pollen cant be crossed with pollen