Can't Load family - ungroup error

[damo3]

I have placed showers within various apartments. These apartments are groups. 

I have made a change to the family, (realigned a reference plane to be equal between two points). Now I reload the family into the project and no matter what I try, I cannot load it into the project without getting the ungroup error. 

Prior to the warning, it states i need to delete a number of dimension references. Which I allow, then the group error appears telling me I still have constraint problems. 

Any rule of thumbs we should be aware of with regards to this? I thought it would be fine to dimension to families in groups, but it appears their is the potential for problems. 

I solved this by going into the problem groups and deleting the family entirely. I will have to reinsert. 

[SteveKStafford]

Changing reference plane settings in families that are lalready being used in a project is always risky because dimensions and other relationships can be create conflicts.

[damo3]

Yes, I guess I can accept that to a point, but modifications is the nature of the beast in Architecture. Clients will always want the parameters shifted. 

My problem is, and perhaps there is no solution, I recieved a warning saying delete constraints and I accepted, so having deleted these constraints, why do I still have problems apparently related to constraints? Interestingly enough, it was only a few groups affected despite the other groups being dimensioned in the same fashion. 

I also have dimensioned my kitchens as they are families, and I have changed them numerous times with no problem, accepting the error to delete references/constraints.  So i guess what I am really trying to suss out, is there a trick to dimensioning families so as to not get instance errors for groups. 

I am just thinking out loud here, but dimensions are outside of the group, why are they having an instance based effect on the group?

My experience with Revit over the last few years has led me to believe there are rules and orders to follow, if followed correctly, Revit is fairly straight forward... wandering what (if any) the rules/order were in these instances..