Some existing film entries here also have Lederhosen and sailor suit scenes (or other historical clothing):(chronologically)
-LHOTP (girl poke bonnet)
-Maman est chez le coiffeur (boy Lederhosen)
-You Can't Do That on Television ((teen) boys and girls in sailor suits)
-Schloss Einstein (boys Lederhosen, girl Dirndl dress)
-Too Young the Hero (teen boys, incl Rick Schroder in sailor suits)
-The Seven Little Foys (girl in sailor dress)
-Hopfensommer (boys, men in Lederhosen, girls Dirndl)
-Young Adam (boy in sailor suit)
-The Little Rascals (1994) (girl in sailor dress)
-Alfons Zitterbacke (1966) (boy in Lederhosen)
-Ein Richter zum Küssen (young boy in sailor suit)
-Cheaper by the Dozen (1950+sequels) (girls, boys, women sailor suits)
-Our Gang Follies of 1938 (boy in sailor suit)
-The Music Man (1962) (boy, girls in sailor suits)
-Kleiner Mann - ganz groß (1957) (boys in Lederhosen)
-Young Adam (boy in sailor suit?)
-Pünktchen und Anton (1953) (boys Lederhosen, sailor suits)
-Summer Holiday (1948) (boy in sailor suit)
-Summer Magic (teen girl in sailor suit, boy with collar)
-Rebecca of Sunnybrook Farm (1938) (women in sailor dresses)
-Der kleine Vampir - Neue Abenteuer (boy in Lederhosen)
-Pollyanna (1960) (girls in sailor dresses)
-Johnny and the Bomb (boy in Lederhosen)
-The Waltons (teen girl in sailor dress), Season 6
-Mensch, Oma! (young man/teen boy in sailor suit, boys shorts)
-Da wo das Glück beginnt (boy in Lederhosen, woman leather clothing)
-Young Dragons: Kung Fu Kids (series),boys sailor suits "Hao xiao zi di er ji"
-The Vanishing Virginian (teen girl sailor dress, teen boy knickers, bibs)
This list will be regularly updated.
Bibs and Lederhosen have something in common. Also many films are with Lederhosen and sailor suits, although sailor suits are more common in northern Germany (and other countries) and Lederhosen in southern Germany, Bavaria (+Austria, Switzerland, Italy etc).
I think my new blog has not been crawled by Google yet. I also made a spelling mistake in the title and had to rename it. I have to cross-link it also to other blogs, but most Lederhosen blogs are shopping site. I have added some links but not blogs.