You should contact a few dealers and ask what they say. Did you ask Harold HPA?
I believe the suspension bolts ARE stretch bolts. Meaning when you torque them up... they stretch. Sure you could reuse them... but they will break sooner or later. IF it were my car I wouldn't take that chance. Especially when that bolt is holding up your car!
As for wheel lug bolts. No those aren't stretch bolts. BUT they do wear. IF you constantly swapping out wheels... it would be a good idea to inspect your lug bolts and maybe replace them every year or two. It was user: Drivehard who first reported how his 128i lug bolts had stress cracks from all the DE events he does with his car.