Yes it adds, that's the answer from Kevin in some other threads and I think TL. A very tough add. You have to work harder when they are reinforced.
From SL rulebook:
Advance Turn Counter
Compare the total value of active Enemy Units on the
Battlefield to the Half/Destroyed numbers on the Battalion
If the Battalion has been reduced to Half strength, subtract
2 from their Tactical Move rolls until the end of the Battle.
If the Battalion has been Destroyed, you may end the
Battle. The Battle automatically ends when you run out of
If additional Units are added to a Battalion, add their
values to the Battalion’s total.