Advice pls - convert multiple SATB 7x11 to 8.5x11 using Template Sets?

I have 10 individual SATB pieces in 7x11 Octavo Format. Each piece is a single flow in a single Dorico file. I want to print them all in a spiral bound letter size book. I expect to do some re-formatting but wish to reduce the manual fiddling to the bare minimum.
I suspect that Page Template Sets would help with this, but I find the concept confusing. My aging brain.
Any suggestions would be much appreciated!
Thx, Randy

Lock the layout first. Then increase the page size in layout options. I would probably also increase the inside margin to allow for the binding. You may find out you do little or no reformatting.

Thanks Dan! Locking the layout was a big help, and I managed to figure out how to create a new Template Set which will make it easier going forward.

Also, when changing the page size, adjust the margins by the same amount so the working page size stays the same. So, in this case, add 0.75 in to the top and bottom margins. This will keep all your frames the same size and relative position.