Impetuous movement and interpenetration

In the Advanced Impetus rules it states that forward involuntary interpenetration is no longer allowed if the troop types can't normally interpenetrate - a change from the rules book which had the interpenetration occurring with the interpenetrated troops being disordered. 5.10.2

My question is, what happens to impetuous troops behind troops they can't interpenetrate?

eg a line of impetuous CP behind a line of FP?
Do they move up to it and stop?
Try to wheel and move around the front troops?
Something else?

A messy logjam ensues.

When fighting Impetuous types with an Infantry army this is my favoured tactic, they are very predictable so you have to manoeuvre to take advantage of that predictability.

The timing of the advance is very important with impetuous troops. The can get backed up. Especially with fast impetuous CP like Norman cavalry. On the other hand, you can use FP to hold the CP back without the CP being on opportunity and then echelon out of the way with the FP and let the CP go.

Further to that, if they no longer push through the unit in front, does this now Disorder the Impetuous unit and the unit in front?   I know it doesn't say that in the rules.   However, with no penalty, that would be a way to stop Impetuous units going out of control because the amendment says that they just stop.

Dennis