I am returning to working in InDesign for my book project after almost a year. Now, I am rusty. I can't remember many things I knew when I was working on it last October. One of the things I can't remember is the thing about section starts. In the example below, there is the little black triangle at page 100 and at page 110. Bot are starts of sections of the book. I have inserted spreads 108-109 and 112-113 and now I want that same 'start' on page 108 as I am starting a new (extra) 'chapter' of the book there.
Wen I right-click page 108 and select the 'Numbering & Section' options and say it is a new section, I get this warning:
And I am at a loss what to do now.
Can someone help me rememberhow this worked or point me to the 'refresher info' I obviously need?