[BroadcastMXF]

Recently our company received several thousands of MXF files from our Transcoding partner, all of them with the same UMID in the header.

This makes the files useless in our post-production and playout system.
For example: the AMA link in Avid won't import multiple files from this batch because they all have the same UMID.

Our Transcoding partner is looking for a solution, but I want to actively search with them.

Is there a tool we can use to change the UMID's without having to transcode the files all over again?
Basically opening the container, rewriting the XML data and closing and saving it without touching the video?

A proper brainteaser... anyone?