Making an ePub Sample for my Book on Apple iBook Store, Pages format

Hi to all, I have published an ebook on the Apple store, I am wanting to make an ePub sample using Pages. Pages can export ePub format. I am wanting to do something "simple", taking the current book, and simply deleting some pages to make a sample. However (wether I am in "word processing format" or "Page layout format", when I delete pages, it "disorganises" my pages document. I'll explain: I have some pages made out of 1 column and pages made of 2 columns. When I delete a page, the texte moves in the document and text which was placed on a 2 columns page finds itself on a 1 column page... which changes all the presentation: please see pictures below. Any ideas how I can avoid this? Making a PDF would allow me to delete pages easily but I can't export ePub from PDF can I? Many thanks to all in advance.

When deleting page 10 for example: 

The illustration on page 15 finds itself moved to a 2 columns pages... and becomes small...