Actually, the main drains were not a big deal at all... I was a bit nervous about the foam funneling correctly to the drains, as I installed the drains to about half the depth of the foam bottom to achieve that effect. In the end it worked exactly as I expected it to and the main drains are golden. Even setting them with concrete and everything else associated was a non-issue in the end.

About the only thing the main drains do is not allow me to adjust the liner once the holes for them are cut. But I was concerned about the water pressure pushing the liner into the drain holes too agressively, thus causing wrinkles if I filled it too far before cutting them in... So I waited until the water was about 4-5" deep and then mounted the trim rings, cut out the centers and put the covers on.

As I am filling already today I am noticing the liner on the walls looking good 70-80% around the pool, the one side that has the seam an extra inch or so up the cove compared to the other side is the "problem area". If I can get it set smooth everywhere but there I may just have to live with it folded a bit near the bottom, if that is even doable without totally messing it up. I would just hate to have to fill, then drain, then fill again to get this all figured out.

I have three hoses going into the pool to fill it up at the moment. There is still plenty of water pressure in the house, so I may just get a faucet adapter and use the mudroom sinks faucet to aid it even more...

I hope everything works out, just that it seems like everything about this project has been "against me" in regards to time and things going right the first time without having to constantly rework things. For me that is a big deal since I am meticulous about designing/engineering/planning and execution so that stuff usually just "falls into place". And some of the stuff has, just that a bunch of stuff has just been a major PITA.