Nope -- that's not how it works......
For the past decade at least, Airframers/Assemblers such as Boeing bring suppliers on-sight during what they typically refer to Joint Definition Phase. Essentially this is when the aircraft subsystem specifications are developed. the suppliers are on site through at least critical design review and work side by side with Boeing engineers to develop system level and component level specifications. Often times this is even before a contract has been awarded to the suppliers... Reasons for this:
1) Benefit to Boeing... they get a specification that they know can be produced and they get the expertise of the suppliers. Avionic engineers know avionics, etc.
2) Benefit to Suppliers... they know when the specification goes out to bid for contract, it is in a form of which they can meet and competitively bid on it.
Often times there is more than one supplier for a particular component or system working with the airframer to keep things competitive.
Been this way for at least a decade..... those on the automotive side know the same drill.