DIF export: merge of 1.5 1.5.1

Hi this a question mostly about the TGE engine and merging. We are in mid project and wanted to make use of the export as dif option with embedded static meshes. We've been using 1.5 and just recently did a merge to 1.5.1 to do just that. However after what we thought we had a clean merge the DIFs exported through "export DIF" with embedded static meshes still do not show up in game. I did try the same DIF in both a clean 1.5.1 and the merged 1.5.1, successful in the clean and not in the merge. So, apparently there was something in the engine that was not merged correctly, so my question is:

Where in the uncompiled 1.5.1 engine is the code that allows the use of embedded static meshes???
Thanks a bunch -