getting a second (and third) remote entry solution

[oldskewel]

Glad to see the plan is working for you.

So that solution of buying two new cheap Chinese eBay fobs is the newer substitute for my older solution of buying old used Genuine BMW diamond keys on eBay for about the same.

I think for the purposes of the plan, the two are equivalent. They solve the problem of keyless entry, and that is it. But unlike the used genuine key solution, you could have the key blades cut to match your mechanical locks in the driver's door, ignition, and glove box. ...

But there is virtually no way that they will ever be able to solve the EWS problem to allow you to start the engine. The eBay seller saying to take it to a locksmith for that is not really practical. I won't say it is impossible, but probably not cost effective to work around the BMW EWS system.

That original diamond key you already have will still solve that EWS problem for you, even if the keyless entry no longer works on it. So something to consider is (first don't lose it or consider it worthless even if it falls apart) to keep it in the car permanently for the sole purpose of keeping EWS happy. I don't know how close it has to be to the ignition lock clinder, but you could consider installing it on the inside of the steering column panels in there. That would effectively bypass the EWS system, and you could use as many $10 keys as you want, having the blades cut, etc.

The EWS system is not confused by seeing non-conforming EWS chips in addition to a valid one. That's how my solution works = new Genuine BMW valet key (with valid BMW-programmed EWS chip) + old Genuine BMW diamond key (fob with blade cut off, with invalid BMW EWS chip for a completely different BMW). When running my PASoft scanning software, I'd see EWS warnings showing an invalid chip present, so it knows it's there, but will not stop it from allowing the engine to start, as long as a valid one is there as well.

I don't know whether the EWS interrogation requires the fob to be powered with a battery. So if your battery (the rechargeable Panasonic 3V) battery in the genuine diamond key is dead or the circuit has broken, but the EWS is intact, it might or might not work. The cheaper Genuine BMW valet keys do not have any battery; the interrogating signal coming from the antenna surrounding the ignition cylinder also instantly powers the circuit so it can receive and respond to the coded signal. So that shows it is possible, but I'm not completely sure yet whether the EWS in a diamond key has the same capability to work without a battery.