You see 162489 and 162990, How can I merge them ?
In the TFS Merge help - http://msdn.microsoft.com/en-us/library/bd6dxhfy(v=VS.100).aspx -, you see in the 2nd example how you can merge one changeset:
tf merge /version:C137~C137 branch1 branch2 /recursive
Is that what you are after?