Reference plane help

[t1.shep]

I've struggled with this for as long as I've known about the family creator...
when you have reference planes setup, but want one to be tied to another, how do you define which one moves and which one stays put?
Much easier to show than describe...see attached image.
I have a door. Height and rough height reference planes defined and dimensioned. Now I want to add a trim width parameter. I add a new reference plane above the rough height ref. plane (dimensioned to 1'-3"). When I add a parameter to that dimension of something different than 1'-3", it tries to move the rough height reference plane.
How do I make it so that it doesn't try to move the rough height ref. plane and instead moves the new trim width ref. plane down to the rough height ref. plane?
I've been able to work around this in the past, and usually it has to deal with the order in which parameters are assigned to ref. planes. However, I find it extremely cumbersome since I don't always know what I'm going to need to add to the family. I hope there is another logical way to deal with this?

[Munkholm]

Without having the actual family to break down, it´s a little hard to tell, but im guessing that you´ve said it yourself... it´s about order, When you assing the parameter in the first place, leave it to 1´- 3",APPLY and THEN change it.

Try posting the family, if you need more specific guidelines....