I asked our GML and did a little digging on the 501st Forum, which points me to the Detachment.
It seems this is handle through the Detachment, but to be honest I am a bit lost (so our GML said too).
This is the thread I found on the 501st Forum:
https://www.501st.com/forum/viewtopic.php?f=15&t=98625&p=1239067&hilit=detachment+affiliation#p1239067
Any help appreciated! Thanks!