You could be lucky - I was for the first 18 months with the 4 I added. I couldn't understand why everyone kept saying they were a problem.
I do now. Lost one, so added two. Then lost another. And another. And another. All to the same modus operandi... seperation from the group followed by slow starvation as the isolated one seemed to lose the will to live outside of the group.
I have two left now, and will not be adding any more...