How to merge 2 XMI CASes?

[Ngan Nguyen <nl...@gmail.com>]

I would like to ask for your ideas about the problem of "Annotation Merging"
in UIMA. I have 2 XMI CASes for the same text collection:
-X contains annotations of the types {A, B, C, D}
-Y contains annotations of the types {A', B'}

I would like to merge these two CASes into one CAS containing {A', B', C, D}
because I did some changes in the type system.
What is the simplest way to do this? I don't want to run the AE on Y to
produce C, D again because it takes much time. We cannot use more than one
collection reader in a CPE?

Ngan