Speaking of Find-a-Grave — there are a few entries from Catholic cemeteries in Rudolfsgnad and Deutsch-Etschka that look like they were posted by relatives. But someone has also put up a page for the mass grave at Rudolfsgnad, and then made pages for those people known to have died at that camp — nearly 6400 memorials: https://www.findagrave.com/cemetery/2457820/rudolfsgnad-concentration-camp I found the page for one of my great-grandmothers there, and was able to link her page to the one I set up for my grandmother, so I’m sure others could do the same. Note that Find-a-Grave only allows the modern place names to be used for locations, but you can always add other info in the bio.
Cheers,
Linda