I have 2 .net dll's which I expose to COM using REGASM. In order to simplify referencing within a COM client I would like to make these into one file.

I have tried converting both files to IDL and then copying the contents of the Library section of one into the other and then compiling back to .tlb with MIDL. This works fine for the TypeDefs within the second IDL however it seems to fail when it comes to the interfaces I copied in. OLE/COM viewer can see the interface definitions but when I try and use the TLB via COM it cant find the interfaces that I copied in.

I wanted to make sure before I spend too much time on this, that it is actually possible to meagre IDL's in this way.