E61 Key programming

[Carouser]

I have only a single key for my 2007 e61 LCI and I am in the process of DIY for a new one. I have a new 315Mhz key fob, but the AK90+ that I ordered only reads the old key (with the wrong milage) and not able to program CAS as the vendor insisted it was able to do (they are investigating. but I will be returning the unit) . I will probably get the Hitag2 v3.1 for key programming as it seems like a reliable unit.

I am looking at the easiest approach to this as there are varied methods of reading/writing to the CAS module.  I found a copy of ISTA-p on this site, but the cost for ICOM Next cable is pricey even for a Chinese clone. Removing the CAS and using the bench method with additional hardware is the next option.

My question: Could I use my K-DCAN cable with BMW standard tools to read the CAS /key memory in the car, and copy one of the used keys that is not my current key and marked still in use to program my new key?  This way I do not have to write anything to the CAS and cause any mischief. The new key would have all the settings i assume for comfort access just like my current key, and it would be individual to another driver preferences.

Is this a plan? Or is there a better recommended way to do this that most people here use?