I have the different branching one, densely branching. This is how the place of division looks like (made likely during collection, not by me):
Chisel and hammer could work here as well.
Guessing here, but if the branching is sparse, as here:
the whole branch could be removed, just as for candycane coral.
One more thing: some had very good experience (with no photos before and after) with fragging by Dremel. For me, it was a disaster: the blade was too shallow, and blade - and/or mandrel - teared soft tissue ragged with massive die-off in the next couple of days. Recovered, of course, but the grey necrotic tissue had to be siphoned out.
On the photo you can see the single polyp frag. It was glued and recovered well.
But in any case, this was not Dendrophyllia.
What works for duncans and tubastreas, may or may not work doe dendrophillias. Maybe someone from their keepers chime in.