Summary or Totals in Relationships

[crazybake]

There are three tables:

Services
ServiceTransactions
ServiceTransactionLineItems

Relationships:

Services:materialName::ServiceTransactionsLineItems:Material_FK and Services:MaterialYear::ServiceTransactionLineitems:TransactionLineItemYear
(Services may change from year to year, and within one transaction you might line items for both current and future years.)

ServiceTransaction:TransactionNumber::ServiceTransactionLineItems:TransactionFK

:Services:MaterialBudgetAllocation is a user entered number.
What I am hoping to do is: Get the yearly total amounts of each material (Material_FK) and subtract that from Services:MaterialBudgetAllocation to get a remaining amount.