I'm taking a breather around putting up the panelling in the back sunroom.
Small woodworker tip might come in handy for others? There's an octagonal window (non-opening) from the 3rd bedroom into the sunroom. 2 ways to handle this.
1- remove exteror frame after using masking tape to mark the pieces so you can put them back up in order. Inner parts got a-b-c etc, outer got 1-2-3 etc. Arrange the panelling of that section so one of the cuts is center of the window (easier than cutting a hole in the center of a piece of thin panel wood).2- more of a hack job but sometimes you cant remove the frame without damage. Dont remove frame, add small 'ceiling rail' pieces mitered neatly to extend the frame over the edges of the paneling (hides where they fit against the wood).