Option to write metadata in DNG files

For my archive and some clients, I want to add specific metadata (e.g. "persons shown" which is not available in C1) to large sets of files. Usually I import RAWs directly into C1, do my culling and editing there, then "sync metadata" (so my star ratings are being written into .xmp files). Next i use Photo Mechanic to fill all needed IPTC fields with their token-based metadata system. Back in C1 I load metadata back into the files and then export.

I cannot do that with my Leica DNG files. Other software ignores .xmp for DNGs, so ratings given in C1 are lost. Also: Metadata changed by Photo Mechanic (or any other software), gets written inside the DNG and cannot be loaded it into C1 once it has already written its own metadata (like star ratings).

I understand C1’s principle of not altering RAW files, but DNG is a standardized, openly documented format designed to allow metadata changes. Please consider offering an optional "Write metadata to DNG" function (even disabled by default for all I care). If enabled, C1 should check DNGs for updated metadata on “Load Metadata”.