Thanks to all for the comments and ideas, and especially MrYoung for his assistance and an expansion panel! Many Thanks!
With an expansion panel I think will have switches on the doors, and a suitable PIR in the garage space, and also now a PIR in the small workshop that will be attached...
I have a house with a Scantronic 9100, with 4 circuits.
3 circuits just have a single PIR on them, the fourth has a PIR and 3 magnetic door switches on it. Also there is a second keypad on the first floor. System has worked reliably for many years.
I read coments that this panel is...