I think what you are referring to is a technique called grafting and it involves using a host plant as a multi genetic mother. The plant has an ability to heal itself and when topped, split in half downward, and then another branch can be cut into a V shape, applied gel to, and then held in place between the split. The plant will use it's healing ability to "join" itself with the branch like a human would react to having a limb severed and stitched back together and re-heals. It looks pretty frankensteinish. Theres a thread about it somewhere in grafting topics where a guy has about 5-6 strains on one mother plant. Gotta think outside the box sometimes