I found this site
www.idflieg.de which is easy to use and gave me the following info. on Ltn.Schwerdtfeger(sic)
Soignies(100) Is this the aerodrome number?
Then they have him with 252 as already stated with (150) in brackets.
After that is a listing of other units? under thwe heading, quellen (swell?)
as follows....
(100)verlustliste(150) S.315(144) S.326
This is a very good site for casualty listings, and they give a whole load of links. All help still more than welcome.