Mass Allocation on Dependent Value set values

Hi All,

We have COA with Company, Cost Center, Major and Minor segments. Minor segment is dependent segment on Major segment. Our company has decided to define Mass allocation on Minor dependent segment. Lets take  example :Minor segment is having 3 values : A, B, C

We can't create parent and child relationship for dependent valueset. Hence, we can't create parent value for minor values. In this scenario, how to define formula to sum of 3 minor values to allocate expenses.

Regards

Avaneesh