Solved! Go to Solution.
The point of using the "Register with existing data" options is that the data present in both the geodatabases should be exactly similar. Only then is this option viable.
This is the reason we need to create dummy DTs with the same name as the existing DTs, just to create the replica between the two.
I was not able to create a replica with the 'register existing data only' option when my data in the parent SDE were in a FD and the child file GDB has the same datasets as feature classes in the GDB. The FCs in the child are copied from the SDE so the global IDs are the same. Unless I am reading this explanation incorrectly, there still needs to be a FD for which the replica toolbar (ArcMap) looks for when replicating-- if not, there are no datasets listed on the dialog, even though they are in the GDB already (just not in a FD as in the parent SDE)
I verified the work around about moving the data out of a FD in the child after replication, but that seems contrary to the above post. Different staff recommending/saying different things is nothing new, but if it is possible to one way replicate with data from FD to FCs I would love to know how to do it--- and to have this all explained in the documentation somewhere (but wont hold my breath! )
There is a bug associated with this -
that has apparently been on the books since 2010! According to the analyst I am working with, it is supposed to be addressed in the next release, but considering its been over 5 years and a new release just happened, I am skeptical.