Add conditions to make it so some products are not included in the FedEx quote

I have ran into situations where clients ship their items using two or more services. For instance some items go out USPS flat rate boxes and some items go out FedEx. Since flat rate uses conditions it is (somewhat) easy for me to setup which flate rates are shown to the cx. However, the FedEx quote is always calculated and there does not seem to be a way to tell it to ignore certain products, or only get a quote for these products if they are ordered with these products, etc. Something like that would be very handy to have.