How to add "RAW Data Object Width/Height/Length" to Instance Data Definition. For attachment to existing standard .dgn elements

I have existing dgn elements and cells (not authored in AECOsim, no parts/family definitions).

I am attaching my own user definitions as instance data.

My question is how to add object dimension data to my user definition.  Ideally I want to attach object dimensions Length/Width/Height.

Currently my definition file requires manual input of these fields via schedule or properties.  I want this to be done automatically, by reading the RAW property data of the existing cell or element.

The high range minus low range values can give me XYZ values.  Hopefully these can be utilized.

How can the above data be incorporated into my AECOsim/OpenBuildings Definition File?

Thanks