Need help with my ERD.
I am new to FileMaker. I am trying to design a solution for my business so my invoicing will be more efficient. I am running a small electrical business. Sometimes I do my own jobs where I charge fixed price and sometimes I supply labour for bigger firms where I charge hourly rates for each person I supply. This rate values are sometimes different and sometimes the same for clients. Each rate has got its name which are the same for every client. I.e. Rate A, Rate B, Rate C, Fare, Travel Time, OTA. Also client can change a rate value over time. I can't figure out where shall I put my Rates.At the minute my ERD looks like this.
customer ---//Contact ---//Invoice//---InvoiceLineItems//---Product
Any help much appreciated.