Hi Rahul,
I dont have much of the trouble keeping them together but you need to consider the following (based on my experience):
1. large tank especially in length/height (I know it sounds common but sometimes people do not following the common sense)
2. huge amount of rock works for the BFs as a hiding place
3. avoid keeping small/med size angels but only with Angels larger than 10" as they tended to ignore the BFs. Most of my angels are larger than 12"
4. the sequence of introducing BFs into the Angel tank, deep water BFs always the last especially Burgess. Personally I do not plan to have any Burgess in my tank.
5. Feeding sequence: I feed angels with "jumbo" pallets a minute before "mini" & "flakes" for BFs
All in all, my angels do bully the BFs sometimes but not often as the BFs are in their way but most of the time my BFs swim near the rock work in the bottom while the angels cruise around the upper part of the tank (40" height).
Good luck!