Since you are well covered, I refer you to the first line of my reply.
Your oil consumption is high enough to be a failed guide but it is most likely just seals. BTW the insurance company is not going to buy you a fix based upon an internet conversation. We can give you advice, but mine would be to use your insurance to develope a good relationship with an expert. If your insurance covers internal engines but not mixture forming devices that is not a reason to blame the engine.
Whatever your problem is it won't change because you can afford it or not!
Whatever the cause, you should not wait to solve the problem. Oil consumption at that level will destroy your catalytic convertor in a short time. It may already have and be part of your problem.
Bosch Master, ASE Master, L1
33 years MB technician