I'm just testing this fictional mod. In some of the air groups screens I can't see the option to get pilot replacements. Also in such groups there is a number in parentheses next to the number of ready pilots. At the same time other squadrons attached to the same HQ and of the same nationality in the same base have the option to get new pilots. Oddly enough, the number in the parantheses next to the ready pilots in such squadrons is zero.
I am attaching two screenshots. I have tried looking this up in the manual but couldn't find anything.
Note: Even though both of these US Army AF squadrons are attached to Far East USAAF, I have removed all restrictions from the HQ through the editor (don't ask why

