Cutting through a still attached BTA

[Swip]

Has anyone every tried to split a bta that's still attached to a rock?
There are many stories about things like a rock falling on one, cutting the bta which then split after that without any problems.

I've propagated quite a few the "normal" way(pulling it off the rock first, then cutting), but is pulling them off really necessary?

 

[Daniel62]

I think I read somewhere that they would try and reattach themselves if to close together. But am not sure where I read that.