Like mentioned, they are pretty much a no brainer to build especially the T10s. And since you ordered 3, it will come with 2 tubes of Lexel. When I talked to Ali, she said they ship 1 tube of Lexel per 2 cages. And trust me, you can do 3 T10s with 1 tube at the most unless you go crazy like I did with my T10s. My advice is don't. Use a thin bead and push it smooth with a latex glove on that the finger is wet. It will make a nice seam and wont smell up the whole area and take 2 weeks to cure lol.
As for splitting a T10, I guess you could but I know my 3.5 year old female loves all the space in her T8. And I ordered shelves in all my cages since the snakes do seem to like to play on them here and there or stretch out on them like in the Caesar progression thread I got going.