"Shipment.Equipment.Compartment.TotalWeight " Not Present In Rate Record > Rate Basis drop down

Hi,

We are working on one of the requirements where-

Equipment Group is having 4 compartments. While planning Order release, we would like to populate Shipment Cost grid on basis of each compartment weight consumption/utilization basis.

To fulfill this requirement, we would like to create a Rate Record on basis of "Shipment.Equipment.Compartment.TotalWeight " .. but this is not existing in Rate Record> Rate Cost> Rate Basis drop down.

Could you please let us know is there a way to add new record/RBI Item in Rate Basis drop down? OR is there any other way we can populate Shipment Cost on each Equipment.Compartment weight consumption?