This section is non-normative.
Since the ins and del elements do not
  affect paragraphing, it is possible,
  in some cases where paragraphs are implied (without explicit p
  elements), for an ins or del element to
  span both an entire paragraph or other non-phrasing
  content elements and part of another paragraph. For
  example:
<section> <ins> <p> This is a paragraph that was inserted. </p> This is another paragraph whose first sentence was inserted at the same time as the paragraph above. </ins> This is a second sentence, which was there all along. </section>
By only wrapping some paragraphs in p elements, one
  can even get the end of one paragraph, a whole second paragraph,
  and the start of a third paragraph to be covered by the same
  ins or del element (though this is very
  confusing, and not considered good practice):
<section> This is the first paragraph. <ins>This sentence was inserted. <p>This second paragraph was inserted.</p> This sentence was inserted too.</ins> This is the third paragraph in this example. <!-- (don't do this) --> </section>
However, due to the way implied
  paragraphs are defined, it is not possible to mark up the
  end of one paragraph and the start of the very next one using the
  same ins or del element. You instead have
  to use one (or two) p element(s) and two
  ins or del elements, as for example:
<section> <p>This is the first paragraph. <del>This sentence was deleted.</del></p> <p><del>This sentence was deleted too.</del> That sentence needed a separate <del> element.</p> </section>
Partly because of the confusion described above, authors are
  strongly encouraged to always mark up all paragraphs with the
  p element, instead of having ins or
  del elements that cross implied
  paragraphs boundaries.