What is it?
If you have a profile in more than one Tree, Tree merging will allow you to merge these two profiles. If others nodes in the merged trees are duplicated, you will be able to merge these nodes, creating one combined, accurate record of your genealogy using the information in each tree.
This enables the combination of separate Geni trees into a larger tree. (In the future, you will be able to use the GEDCOM import feature to merge your GEDCOM data into an existing family tree on Geni.)
Tree Merging extends profile merging by allowing you two merge your profile with a profile on another tree using a request system for the necessary approval.
Later releases will refine these features and implement more complex ones.