According to a data check: the grandparents dance together in the attic in episode 42 of the second season of Peppa Pig.
"Peppa Pig" is an original European children's animated television series produced by British animation company AstleyBakerDavies and EntertainmentOne, directed by Neville Astley, Mark Baker, Phil Hall & Joris van Hulzen, which premiered on May 31, 2004 on TV5 in the U.K. In June 2015, "The Peppa Pig was introduced to mainland China and premiered on CCTV's children's channel.