I believe the answer is "no". But you can check this yourself. During the
battle in the combat screen, just let your mouse hover over one of the units
involved. You should get a tooltip listing all the modifiers affecting the
unit's combat capabilities, including if it is overstacked.
(BTW, each Field Marshall can command 24 units. A Field Marshall doubles
the command capacity of all corp commanders in the same or adjacent
provinces, _including_ himself.)
--
"I reject your reality and substitute my own."
"Now, quack, damn you!"
Multiversal Mercenaries
You name it, we kill it. Any time, any reality.