Problem adding pages to large document with multiple Sections

Hi.

I’ve meticulously formatted a non-fiction book of some 330 pages, with 12 chapters (defined as Sections with section markers applied.) Paragraph style for Chapters includes “Keep Option “Start on next odd page. 

I have a seperate parent page design for the chapter pages. This is assigned as required.

Here’s my problem: the client now wants to add 20 new graphics, causing, of course, a ripple reflow of all the text in the book. I know how to add new pages, but when I do, the assigned Parent pages that define my Chapter starts do not ripple with the text content. So:

If I have Section 3 starting on book page 27
Then add 4 pages to section 2 (manually or with auto reflow)
Section 3’s start STAYS on the document’s p27 when I would expect it to be shunted to p31
Also, the parent previously applied to p27 doesn’t move “forwards” by 4 pages either, throwing off everything thereafter.

Is there a different way I should be doing this?

ANY help appreciated.

thank you