No.
Events are, by definition, chronologically-organized groupings of photos. So they cannot be rearranged.
The problem, I think, is that you are not understanding iPhoto's structure. The Library is your collection of photos, and EVERYTHING ELSE you see in iPhoto is just an interpretation of some portion of that Library. Events is one view, Faces is another, Photos is another.
Likewise, Albums should be thought of as subsets of the library manually organized by you. This is why when you add or delete something from an Album, it is neither duplicated nor deleted in the Library. Albums are just "filters" or "views" of the library.
If you want 20 events in an Album, you can do that. You can also "merge" Events if you really want to, but again it doesn't actually change anything.