Why not?
Regroup out - 12:11, mimimum time on regroup - 3min, so 12:08 it's 'equal'
Regroup in - 11:36, 32min of latenes won't be affect any change, but all next extra 3 min - was.
As you can't be late more than30min on one TC you need 30+30 =60min and this is 28min extra lateness. 28/3 =9 positions
TC18 11:12+30=11:42
TC18A 12:06+30=12:36
First car on TC18B = 12:11 :)