Reference group cell from shape

[Surrogate]

All sub-shapes into group have width/height which related to group shape's width/height

Code

width=sheet.5!width*7/40

You can overwrite these cells, for prevent resize of sub-shapes

[Soundstorm]

Thanks. I forgot the shape lost all the absolute values I used when ungrouping and starting all over again.

[wapperdude]

Only thing I'm running into now, is the fact that the 'bounding box' is around all items of the group, instead of just around the main shape.

There are two ways, each requires 1 additional step.
1) before grouping, move at least 1 shape to be within borders of the parent shape, then group.  Extra step: open shapesheet of group and scroll to...I think Misc section.  On right side of the listings will be LockCalcWH.  Select (check) this entry.  This locks the recalculation of the bounding box.  Now you can add shapes to group without the change.

2) before grouping, select your parent shape.  Goto Developer tab, and click on Grouping.  Select Change to group.  Extra step:  open the parent shapesheet and do same extra step as above.  Add shapes to group as normally done.