1./KG 30 or 9./KG30?

[DDT]

Hy,
On Friday, may 10 1940 the crew of Oblt. W.Wülknitz was lost following an attack on Rotterdam harbour.
According to P.Cornwell's book they belonged to 1./KG 30, flying a Ju.88 coded 4D+FT. This code would suggest they belonged to 9./KG 30.
Database verliesregister.studiegroepluchtoorloog.nl quotes this plane as belonging to 9./KG 30.
I know that in the later years crews flew a/c from other staffel when loses where high and replacement a/c where in short supply.
But could this be the case here on the first day of te war in the west?
Kind regards,
Dirk