I just got a copy of an original FW190D9 handbook and to my surprise it included a section containing much usefull info about teh WGr21.
1st to say, the D9 could be equiped with the WGr21 just as the A8 or A5.
But no to the more intersting information.
The launch tubes for the WGr21 could be jettisoned.
So when a plane using the WGr21 was attacked by fighter, the pilot could jettison the whole WGr21 installation to get his "clean" fighter condition back.
This was done very easily just using a little switch in the cockpit.
I would find that an interesting option for AH. This would also lead to more FW pilots flying with the rockets attached, cause before a fighter vs. fighter battle they can get rid of that extra weight.