Some say the SR-71 Blackbird is a re-worked Avro Arrow built with a larger budget for speed & altitude???
There are also claims the Concord in both frame & engine design is an up-sized Avro Arrow.
The Arrow was certainly the 1st production fighter aircraft to incorporate 4500psi hydraulic systems.
I can address that one - my father was involved with the development of the J58. There's certainly a relationship in the sense that both are air-breathing high-performance airplanes, but that's about the end of it. The Arrow was meant to be a high performance interceptor and was optimized for that role. Scramble from the runway, climb to 45,000 feet as fast as possible, accelerate to mach 1.5 and engage invaders with missiles before they can drop the bomb on Toronto. It's the sports car (probably a 289 Cobra) of the airplane world - not much range or payload, but good handling and performance. The blackbird, by comparison, can only be compared to a land speed record car - something like the Blue Flame or the Thrust SSC.
About all the Arrow's design parameters have in common with the mission profile of any produced variant of project oxcart is supersonic flight. The blackbird was the first airplane in history to be optimized for supersonic cruise. Time to climb doesn't matter, the 'weapons bay' on the paper F-12 variant theoretically held all of two missiles (sneaked in beside the forward landing gear), and the primary payload (recon nose pod) went where fire control radar would have to be. The Arrow is of rather conventional (riveted aluminum) construction. The blackbird is
all titanium and radar-absorbing plastic. The blackbird actually gets its best fuel economy at maximum cruise. The arrow, like all fighter interceptors, has a maximum design range of about 400 miles, and less than 300 miles if a supersonic sprint is required. The blackbird has just settled into cruise altitude (70,000+ feet) and speed (mach 3.5+) 400 miles from base, after hitting its first tanker for a big pull of JP-7. Oh, and if you try to roll a blackbird you will die - they were called 'sleds' by their pilots for a reason. Definitely not a dogfighter.
If the Arrow has a direct descendant, it's probably the MiG-25. The blackbird's descendants are not officially acknowledged...