Can't dimension to objects in group?

[PDSF]

We have a simple detail group (2 circles) representing a bollard in plan. This is nested inside another detail group with all the bollards, so it will update when changed in multiple plans. (We don't actually model the bollards because the garage floor slopes and placing them is a hassle.) I am unable to dimension between these groups without getting the Ungroup error (see attachment). Is this just a Revit limitation or is there a workaround?

[nhlakaniphoMEM9Q]

Hi there, 

When you're in the group you would need to draw a Reference Plane or a simple line that you can use as a reference point for the dimension. Once the Reference Line or line is drawn then you'll be able to create your dimension appropriately. 

[jay_colcombe]

The group contains specific information as regards positioning in relation to other items etc. so trying to drive this from a dimension outside the Group will cause such a warning as you would be changing ALL groups of the same name!

What you need to do is When crating the Group already have the dimensions inside the group and this will create a detail group so when you do click Edit Group the dimension it is associated with the group directly 

[imankassab2015]

When you Dimension things inside the group edit it will be separated as attached detail group so all the warnings you will get ride of it 

Or use a small model line LI as reference outside to the dimension both work well