There are too many un-disclosed pieces of information about this.
First - a 12 seat jet - is a good size business jet - And most pilots who fly a 12 seat jet have worked their way to it, they didn’t build time flying on someone else’s check just to meet the insurance requirements. Some of them even spent years, full time to get to that point, even through accelerated programs you are looking at 8-12 months for the ratings (not including type). People like myself who went through these programs then spent several years either instructing or flying some other job to just get the opportunity to move up to even the right seat of a little bigger aircraft. Or even to a high performance twin piston poper. I have spent a little less then 5 years working my @$$ off, and just now have had the opportunity to fly a Beechjet, as a SIC. Even after instructing for 2 years, and flying other aircraft on the business side, I will honestly say that flying a business jet single pilot IFR would scare the crap out of me until I have a significant amount of time in the aircraft.
Second - a pilot (this co-pilot) who does have time flying business jets and does not want to take the captain seat is hiding something or your not telling us everything.
Third - There are thousands of pilots out there who are already very qualified to fly a jet for this lady. Why would she want to spend over $100,000 dollars on training you, when there are so many others out there? I understand that you have a history with her, but she can find plenty of other pilots out there that she could trust just as much. There are a lot of us, there is bound to be at least a few hundred others that can match the personality type.
Fourth - There have been several other requests for you to clarify your situation so we could help answer your questions, and you have provided none of that. It sounds like a lot of BS.
TO get a rise out of people, come up with some other BS story that is a little more believable, and be straight up with all of us when we are asking questions. The only reason for the questions is because it is a very unbelievable situation, especially when we have a better background in what you’re asking. You want straight answers then your going to have to give straight questions. There are too many un-disclosed pieces of information about this.