I think the pros here should just relax la.
No matter how people talk and warn about uncle bobs, there will always be uncles, nephews, cousins, brothers, sisters, friends who want to shoot in a wedding. All we can do as service providers is to manage, and not get too "hot" about it. After all, they are all relatives/friends of the bride and groom. No point getting all riled up, and in the end spoil the joyous occasion.
There are ways to manage them and the situation, no matter how stubborn they get. I strongly believe fostering a us vs them attitude here in the forum is not going to help the situation, but make more people emotional about it.
Also no point complaining about stealing poses, etc... Great photographers lead the way and create new poses. Poses are not that secret or magical anyway. Just read the scene, lighting and go with the flow and create. When the going gets tough, the tough gets going.