When either of those 2 Crews, Vickers or Mortar Emplacement lose 1 Member and then have a squadsize of 2 they cant crew their emplacements anymore.
Meaning with a 2Man Mortaremplacements Crew i can build infinite Mortars which are still crewable with normal inf.
Vickers is kinda different because they cant relocate and only got uses on their build, but still i they cant crew their built emplacements.
Greetz Lu
P.s.: Keep my english mistakes, i make enough