TLDR: here is some unsolicited advice, I sincerely hope it helps you.
If you are doing the maintenance/repairs on this Buick fleet yourself they won't be too bad once you get them sorted. Parts availability will be a concern. However, GM does not have **that** much variation in hard (mechanical) parts. Trim and features (who said Digital dash?), however, could be your Waterloo.
You might want to modify the deal with the kids to "you buy the parts, I'll do the work." As for the girlfriend, well, "happy wife, happy life."
As for the "No longer have the income," I think I get that... maybe you have an opportunity to improve the income side of your situation. If you are repairing your own cars it might be worth a look-see because that speaks to problem solving and mechanical skills. For more on this topic send me a PM.
AAAAAnd visit your local pick-n-pull as you need parts, there are many parts (thermal breakers, HVAC damper servos, trim parts) that you flat out can't get otherwise but they will let you have for a song. Plus over time you *may* notice they will keep cars with parts that fit yours around more -- they don't pay much for junk cars but they do have to pick and choose which ones to display vs. crush -- part of how they decide is observing what customers are asking for/pulling from.