Editor's note: This is the final installment in a two-part series detailing the consulting work former Realtor association executive Jerry Matthews is conducting for the National Association of Realtors to facilitate association mergers.Realtor association exec-turned-consultant Jerry Matthews says that when he's working with associations that want to explore mergers, he can "get them to the preacher," but "it's up to them to get married."Although there are compelling reasons for Realtor associations to consider consolidation, there's also no shortage of issues that can derail merger talks -- even after they're well under way.Having an objective third-party mediator "is probably the biggest thing" determining whether merger talks will succeed or fail, he...