Designing a new jet engine by two companies (even worse from two countries) is a plan for disaster. If they ask me, I would tell them why and it would save them billions.
Who want to give out their own
secrets? Besides politics, they will spend more time to point other
folks' faults such like the politicians supporters here. It would be
nice for the designers and managers to jack up the air miles so it is
good for the airline and eventually good for the manufacturers / jet
engine makers. There is always a silver lining.