I think this article will be useful for you Dynamic Integrations for Multiple Hyperion Planning Applications

If you want to merge dimension elements tree, you have to prepare table with difference between planning dimension and source table.

For example our solution:

1. we created view in the hyperion app database which generates dimension hierarchy with elements and it attributes and properties

2. loaded data from view to the staging database

3. compare elements properties and attributes with the new source

4. insert/update/delete only differs between  element lists