hey everyone thanks for ur replies and help, they are 3 in a couple of months and we think they are now in their heat, they last had one around 5 months ago so its about a month off.
we have been having them sleeping in cages next to each other in the same room and putting them in the cages during the day for short periods as well. the problem we have is we have had a few small fights in the past and put them together again after the fight but this time as soon as their feet hit the floor they charge at each other and try to kill each other.
they have not benn spayed yet though we are now seriously looking at doing it.
Today we took them for a 2hr walk with muzzels on to begin with but we had a friend along with her german shep. so there was focus much more on a pack feelin we took their muzzels off roughly half way through the walk and they were walking well together although when we stopped to chat to another friend tension was starting to build.
we are hoping that by sleeping in cages next to each other again tonight and taking them for a long pack like walk tomorrow morning and tomorrow night might help bring them back to how they were, though i dont think we can ever trust them to be allowed together and certainly not in the same crate.

Any further comments and advice would be great, and thanks again so much for your help so far
Tom