I don't think this is too complex, but I can't figure out what what the correct solution is.

I have 6 tables: Customer, Project, Rate, Hours, EquipmentType, Equipment

All projects belong to a customer, so customers have a PK CustomerId and Project has a PK {CustomerId, ProjectId} where CustomerId is a FK to Customer.

A rate can be defined as being at a project level or a Customer level. A project must...