Moving an object if another is showing.

Hi,

For the sake of it I do not get the proper puzzle setup for the situation described below.
Can anyone help please?

I have a car with two types of undercarriage (groups).
Big & Small.

What I need to do is that when the Big undercarriage is shown by pressing the show big undercarriage button the superstructure group needs to be moved higher.
But only once, even if the Big undercarriage group button is pressed accidentally several times.

When the Small undercarriage button is pressed the superstructure needs to stay low or move back to low depending where it is.
Even if the Small undercarriage button is pressed several times it may only move down the required distance one time.

I have no problem regarding showing and hiding the two types of undercarriage. The trouble is moving the superstructure up & down.

Thanks.