Frag off each head and mount them saperately. When they grow new heads do it again. Why would you not want them to grow together? Thats the way they grow, like Hammer and Frogspawn ( unless the H & F are the wall variety)
The duncan colony i have has like 3 clusters one has 21 heads the other has like 10 the other has maybe 5. I might have to frag a branch off.
if you want it to branch out move it to a spot with a little bit lower light and it will become a little more spindly and tree like if thats what you are looking for
