And speaking of lesser threequels:
The Brady Bunch in the White House (2002)
Inferior made-for-TV follow-up to the theatrical features The Brady Bunch Movie and A Very Brady Sequel, which I enjoyed. The main problem is that we no longer have the absurd Bradys, living in the television version of the 1970's, confronting something that (more or less) resembles the modern world. Instead, the "real" world is just as goofy as they are, as Dad and Mom Brady become the President and Vice-President of the United States.