I've had two opinions on teaching IMC on a Private C.o.A a/c
One from my CFI and one from the CAA
Yes you can teach it & charge for it too!. Get out and do it.
If it is ab inito training you can't teach for an IMC rating even if you don't charge (even if you belong to the same group/syndicate), but you can keep pilots current skills up to standard.
You can guess which was which.
