Okay guys, I have had plenty of neps with basals. I have cut them, traded them, rooted them etc. but I never wondered how they formed. Well a few weeks ago I was having an issue with a N. mirabilis and decided to unpot it to check the roots. I counted five small green sprouts (for lack of a better term) in various spots along the roots. I gently repotted the nep trying as much as possible to keep the roots undisturbed. BTW, they were fine and the plant has completly recovered. I had assumed that these little green sprouts were basals in the making.
Well now one of the little green critters has popped to the surface of the pot and is growing a short distance from the main plant. Once it has some size to it, rather than cut it and attempt to get it to root could I just gently expose the root it is growing from and cut that part of the root away from the main plant. This way I already have a rooted basal and with rooting hormone I would think the piece of root would continue to grow.
I have done this with ludisa orchids as they spread by popping up new plantlets along their roots.