MongoDB Synchronizing multiple Shards
If it's not possible to do it automatically, can it be done manually? So only entries which are not present in the primary database A will be inserted out of one secondary of database B ?

Little Example: In A we got: 1,2,3 In B we got: 5,6,7

What I want is to add 5,6,7 from database B into database A and vice versa, so it looks like this at the end:

A: 1,2,3,5,6,7

B: 5,6,7,1,2,3