Jane Darnell, 13/08/2013 13:19:
Now that I think about it, if you want to create a relationship where Wiki Commons is a client of WikiData, then I think this should be done for galleries only, not categories. Galleries can be easily split and/or merged, reside in more than one category, and offer a "best" selection of images of the subject, as well as offering a link to more images on Commons by clicking through to categories
Wikidata is not a tool to force what you/we think the Right Thing. Interproject links between categories are in the (tens of) millions, hence we need better ways to manage them, not lectures to Wikimedia projects on why it's wrong to do all this. Thank you for the patience.
Nemo