Reclassifying document parent class in FileNet CPE

I have a document class hierarchy such as the following:
Document ----- L1----- L2 ----- L3

My current setup does not allow for creation of instances from L1 or L2, only L3 has allowInstance=true and hence all the document instances in the repository are of L3 class type. I had a requirement to eliminate all L2 classes so the class hierarchy would be: Document ------ L1 ------- L3.

Now, My question is, is it possible (may be changing the Superclass Definition class property)? and If yes, should I expect reclassification for the current instances of L3 type (even though there class did not change).

One option I could think of

1. Create new/copy of L3 class below L1 called L3temp. (with all properties of L3)
2. Reclassify L3 docs to L3temp.
3. Remove L2 and L3 class (should have no docs)
4. Rename Class L3temp to L3.