Script Logic: Transfer value of parent to a base through logic script

Hi All,

Here is hierarchy for an account in my model:

Revenue ->(Parent)

               Sales of Product(Child1 level 1)  ->

                                                                     other children accounts

             Income Services (Child2 level 1) ->

                                                                       other children accounts

I want to get sum of all the base accounts for parent Revenue as I need to transfer this to other model on a base member.