@MLClark The two parody movies had the conceit that the Bradys were somehow caught in a time bubble. The laughs came from turning them loose in our modern world.
There was a third film, a TV movie with Shelley Long and Gary Cole, but they recast the kids because the original actors had aged out of their roles. The short version is that Mike Brady became President of the U.S. No longer as improbable as it seemed when it aired.