Thanks for info exspecially the expedia.com.. I used it long time ago but discontinued for its low ability to find low fares. But the rule is really detail.
it also cleared my question about longer routing from DTW-LHR!
For your advice:
I find success:
DTW-ORD-BWI-JFK-LHR
1600domestic miles before the actual fly!
Anymore transfer I can add?