Choosing between same values depending on previous difference

[T39m]

Hi, guys.
I need to subtract the difference between maximum duration (AH6:AH12) and minimum duration (AI6:AI12) from the duration which has the smallest Factor (AL6:AL12) (if the factor is 0, I've set it so it shows "can't be modified"). This result would be Δt 2 (as seen in the table). The problem is that I have two factors of same value (the factor for activity D (AL9) and the factor for activity F (AL11)) but, for this case, I need only the difference between the maximum and minimum of activity F (because I can subtract 4 days from the max of activity F but can't subtract 8 days from activity F, which would be the result from activity D). Also the resulted value (Δt 2) must be subtracted to it's corresponding activity in table 2 (the one with the steps). Hope I've been clear about my problem.