Dr. Dinkel sometimes gets 2 grafted trees per single rootstock using an interesting method he calls root grafting. Those long taproots we often cut off to fit the tree into a pot can be used as rootstock by grafting directly onto it in some cases. The best success is with a 12 inch or longer root cutting with at least some developed root hairs. Whip and tongue graft as normal and plant it at the graft level or slightly below. Voila!