Word has a handy feature that is doubly handy when building dynamic automated documents: Keep with Next.
If you want to set this for any of your Sections of any depth (including Titles) or any Paragraphs, add a Token Point somewhere at the beginning of your Flow and set it's Label to "Keep with Next" and its value to |||KEEPNEXT|||.
This will make it available in Paragraph and Section Points - you will see this on the left with an Orange highlight to differentiate it from Questions (green).
You can put it anywhere in the Body of any Paragraph or Section Point, we usually put it at the beginning just because it looks nice and tidy.
As with all features, make sure you test your output document thoroughly. "Keep with Next" is best tested by adding extra line breaks above the Paragraph or Numbered Section until you see how it behaves at the bottom of a page when the next element is pushed onto the next page.