For now you will need to take care of this on the application level, i.e. write something which monitors the address for new incoming transactions, and when that happens, divides the funds appropriately. For safety you'd be recommended to directly connect the dividing transaction to the incoming transaction output containing the funds (use createrawtransaction with specific inputs) so that if for some reason the incoming transaction does not get confirmed, none of the dividing transactions can get confirmed either.