How much variation in tire wear/tread depth can I get away with on a stock 2011 E91 xDrive (GM Automatic)?

My rear driver-side Michelin Pilot Sport 4S (225/45R17 94Y XL) has a small leak in the sidewall, strategically located in a spot which can't be repaired safely, but CAN be driven safely if I maintain pressure. I can keep pumping up roughly every week or two for awhile but I don't want to keep pushing my luck until I can put the Blizzaks on. My road hazard warranty will replace that one tire, but not the other three.

The thing is, MaLColM (Mid-Life Crisis Mobile) is an xDrive, which means tire diameters have to be exactly the same within tolerances that BMW has never actually revealed. My cool digital tread depth gauge, averaged across three spots, measures:

Front Driver = 8/32 Front Passenger = 8/32
Rear Driver* = 7/32 Rear Passenger = 7/32

Michelin lists a new 225/45R17 4S at 9.5/32.

So, can I get away with just replacing one tire? Should I move them around so the 9.5/32 shares an axle with an 8/32 (and should that axle be the front or the rear?) If I can't do that, can I replace the rear passenger tire so they at least match side-to-side?

I can afford to replace all four if I really have to, but doggone it, I only bought them in April of 2020 and they only spent a few months installed before I took them off for the winter. They've been on the road a total of ten months during which I've been on mandated maximum telework so I've hardly driven on them. They're still so young…