Board Thread:Support Requests - Getting Technical/@comment-24527829-20150707031108/@comment-131168-20150707225107

This is possible to an extent, but it's not really documented so you kind of have to learn about it by word of mouth like this. It's possible to have a shared repository set up so if a wiki lacks a file, attempting to use it will cause it to check for the same file name at some other predetermined wiki. Setting it up for interlanguage versions of the same wiki is one obvious use. In our case we've got Czech, French, Spanish, German, Italian, Japanese, and Chinese wikis which can all read images from the English one. Use the Contact page to ask Wikia staff about getting it set up.

on a German wiki that's really from the English wiki. You can tell this by the extra text under the image "This file is from a shared repository and may be used by other projects. The description on its file description page there is shown below."