If I read the twin-flame credo right, the twins' individual souls are enjoined to make a complete soul. So what one does will affect both.

Not sure what you mean by grey magic - someone who "works with both hands"? The left and right hand paths? Does white and black?

In a forum section like this black magic is considered bad as it's usually selfish and attempts to control others - or to control resources (such as obtaining money or psychic powers) which may affect another party. It doesn't have to be bad though. in different words, LOA is about improving acquisition and abundance so it appears in various guises.

The other tf should surely feel the energies in use - no? Like Lynn says, it shouldn't necessarily draw either into the other's current. Is that why you asked?