It is said that Yuen Siu Tien had 12 childeren. Known are:
Yuen Woo Ping
Yuen Cheung Yan
Yuen Shun Yee
Yuen Chun Yeung
and Yuen Yat Chor

See: HKCM: Yuen clan

Who has any information on the rest? and their mother(s)?

Well no info on Mama Yuen but Yuen Siu Tien had at least three daughters with two of them trained in chinese dancers. The third sister is known to have served as tea lady on movie set. One of the Yuen Clan Sister was also a stutent of Boston based tai chi master Bom Sik Mak, Donnie Yen's mother and that's through this crucial connection that the latter got to do movies.

As for the sons, there's at least one unknown Yuen brother that a know of named Yuen Lung Kei check here: http://www.hkcinemagic.com/fr/people.asp?id=1900

Siu tien may have also others sons who worked in movies but whose career did not raise above stunt players. It should be noted that Corey Yuen Kwan was often mistaken as one of the Siu Tien boy's and therefore twelve may not be an accurate number.

Still 9 identified out of twelve is not so bad.

Yves.

Thanks for the information!!!

Pieter