I don't think you will get the result you are looking for, best bet if you have say 5 plants that have an unknown sex is to take clones from the all and then label them into sections so you know which came from which plant, make sure to mark the parent to, so you will definately know what came from where.
take the clones and then when you see sex on the parents if it be in veg or in flower then kill off the relevant male clones and you should be left with a good few female plants, veg them out take the strongest for a mother and when the clones are at a size your happy with flower them all and then when there done the mothers you kept should be ready to provide you with some more female clones.