Blank page showing when changing from two column to one column pages

Question

This is the scenario:
Document with two master pages - Page1 has two content areas - left column and right column, Page 2 has one content area the full page width named 'FullPage'
One page set named PageSetOne - with multiple subforms, each with Pagination setting of Following Previous and Continue filling parent.
Second page set named PageSetTwo - this has a single subform with Pagination setting of place on Page2. The child subform has itself a subform with Pagination setting of Place in Content Area 'FullPage'.
     This page set is initially set to be Hidden.
Third page set named PageSetThree - this has a single subform with Pagination setting of place in Page 1 and a child subform with Pagination setting of Following Previous.
[Obviously I am simplifying names and content here].
The problem is this: when in design mode, there is a blank page showing at the end of the document whenever there are sufficient subforms in PageSetOne such that subforms are displayed in the right hand column.
When subforms are removed so that nothing is showing in the right hand column then the blank page goes away.
I have put a marker subform immediately after the last subform in PageSetThree and can see that the blank page is showing after this.
Also, the following problem:
     When in preview mode, the extra blank page at the end does not display (which is good)
     BUT if the hidden PageSetTwo is made to be visible AND there is content showing in the right hand column prior to it,
     THEN a blank page is displayed just before the newly displayed PageSetTwo page (a single column page on Master page Page2).
I have tried every combination of Pagination Place before and after settings and can find no way to avoid the blank pages.
Does anyone have a clue as to what is going on and how I can avoid these blanks showing up?

Answer 1

I have finally managed to solve this problem.
The issue was not a subform extending too far out, it was a pagination setting, as Niall suggested.
I created a blank document to analyse the issue closely, and lo, my new blank doc with all default settings, worked perfectly.
So I revisited my forms and compared the pagination settings subform by subform.
This is what I had to change to ensure that all pages flowed with no extras:
PageSetOne (which is supposed to show using the two column master)
set the top page Place = ‘In Content Area Leftcolumn’ and After=Continue filling parent
All child subforms each with Pagination setting of Following Previous and Continue filling parent.
PageSetTwo (to show in the full page column Master)
set the top page Place = ‘In Content Area FullPage’ and After=Continue filling parent
All child subforms each with Pagination setting of Following Previous and Continue filling parent.
PageSetThree ( back to two column master)
set the top page Place = ‘On Page1’ and After=Continue filling parent
All child subforms each with Pagination setting of Following Previous and Continue filling parent.
I discovered that the critical setting was for PageSetOne. The After setting needed to be Continue filling Parent
Once I had those settings in order then the form performed as required.
This has been a frustrating learning experience but at least ultimately successful.
AJ