Admin Command Bonuses for Fleet Training do not stack.
It appears that Training NACs do not benefit from ancestor bonuses like other NACs do.
I have a stack of five Training NACs, commanded by officers of appropriate rank (VADM, RADM, RADL, CAPT, CDR).
I placed a brand new fighter (with no commander) under the lowest NAC (CDR), whose leader has a Crew Training rating of 150.
After 37 days, the fleet training bonus of the ship was 4%.
I then placed another brand new fighter (with no commander) under the highest NAC (VADM), whose leader has a Crew Training rating of 275.
If the NACs are benefiting from parent bonuses, then this fighter should get less fleet training in 37 days than the first fighter, because this one is missing out on four levels of hierarchy.
Instead, after 37 days, the fleet training bonus of this ship was 6%.
SJW: Fixed for v1.14. See this post: http://aurora2.pentarch.org/index.php?topic=12523.msg151011#msg151011