Jack and Jill - 2009 II is rated/received certificates of:
USA:G
Jack and Jill - 1987 is rated/received certificates of: Philippines:G
The movie "Jack and Jill" released in 2011, not 2008, has a rating of 3.3/10 on IMDb and received a PG rating for crude material.
Jack and Jill vs- the World - 2008 is rated/received certificates of: Argentina:13 Australia:M Netherlands:AL Portugal:M/12 Singapore:NC-16 USA:PG-13
The movie "Jack and Jill" released in 1999 has a 3.9/10 rating on IMDb and a 14% rating on Rotten Tomatoes. It is not rated by the MPAA for a specific certificate.
Jack and Jill - 2009 II was released on: USA: 21 September 2009 (internet)
The cast of Jack and Jill - 2009 includes: Liliana Diazgranados as Jill Hannah Peterson as Trick-or-Treater 1
Jill and the Old Fiddle - 1915 is rated/received certificates of: UK:U
Jack and Jill - 2009 III was released on: USA: 22 October 2009 (Boston, Massachusetts) USA: 5 August 2010 (Woods Hole Film Festival)
Bad Movie Beatdown - 2009 Jack and Jill 5-15 was released on: USA: 13 August 2013
Reason for Living The Jill Ireland Story - 1991 TV is rated/received certificates of: Australia:M
Nikita - 2010 Kill Jill 1-3 is rated/received certificates of: Netherlands:12 USA:TV-14
In the rhyme Jack and Jill, I estimate Jack and Jill to be 5-7 years of age.