Things to come: Building To Existing Structure Is Hard.
When I was a ranch hand for my 17th summer, a large portion of my job was helping an alcoholic carpenter (and by "help," we mean, keep him sober and working) to build out an existing small 700 square foot hunting shack into a rambling 2500 square foot house with an upstairs and a patio. We kept it in the original theme of cedar, with corrugated steel roofing.
A problem was, that a shack that's been standing for 50+ years will pretty much never be square to anything. Wood warps. Ground shifts. Carpenters who thought that they were just building for a humble one-room building had no idea that this would become the great room (central living room) off of which the rest of a rather nice rustic show-home would be built. And did you catch that it stood in the middle, so that we had to build out away from it, in multiple directions?
In the end, it would have been a LOT easier just to have demolished the original structure, and started over. But we didn't. We radiused out our squares to obtuse and acute angles. We checked every abutment with a plumb bob and a protractor before cutting.
That's what I'm doing now, to fit a story of my own, built out of several experiences, to a story of Ambulance Driver's, again.