Don't worry my English is probably worse than Yours.
http://avisynth.org/mediawiki/ImageReader
then if this is possible encode small stream with jpg and join WITHOUT re-encoding with video (so question is: if any tool that allow to join seamlessly two .divx files exist - assume that both have same HxV size, framerate etc)
If there is no tool for seamless joining two.divx files then You need to re-encode WHOLE video anyway... (this is worst solution)
So if You can encode Yours jpg video with exactly same parameters like following video then try to use method described in
http://www.divx-digest.com/articles/joinavi.html
But everything depend from the container (*.divx can be any container like AVI etc with changed suffix).