There is a bit of fluff that contradicts the obvious concept of 12 ASF for 2 Squadrons idea.

In the 3rd/4th SW there was a battle where a "Vengeance & 2 Union-CV's & their 70 ASF" went into battle.

If you do the math you get 40 ASF + 14 ASF + 14 ASF = 68 & your short 2 even w/ 14 ASF on the CV's, but, you also have the 3 Shuttle Bays that could hold 2 Fighters & 1 Shuttle in theory.

So based on that I have always assumed the Union-CV did a full Mech to ASF swap & kept the original 2 Fighters as well for a total of 14.

Think of it as 6 on Offense, 6 ReFuel/Arming, & 2 on Defense w/ the Dropper.

IIRC, The Vengeance has a bit of fluff somewhere with a similar concept of 18 ASF Wings rotating Attack/Rearm runs & 4 to protect the Vengeance.

It also makes sense if you think of the 2 as being "part of" the DS Crew/Staff & the 12 as rotating squadrons that might not always ride on that dropship.