Additional information from another fan/expert:
1.1) Hou Hsia-San (侯小三)
In a portrait gallery from the movie credited for Hou Hsia-San
- "When Hell Broke Loose" (1975), there's a portrait of Ai Chi-San, but Ai Chi-San's name is not in the credits.
I was able to find articles about 2 TV-series starring Hou Hsia-San. The article for the first TV-series includes image of a guy,
who looks like Ai Chi-San:
https://kgbz.pixnet.net/blog/post/323205375 For the other TV-series I found 2 articles: in the first article they mention Hou Hsia-San (侯小三) who appears in that TV-series,
and in the other article there's a photo of Ai Chi-San, saying that this is Ai Chi-San (矮仔三). But I see this quite often that
in different articles for the same movie/TV-series the same actors are credited by their different names.
Here they are:
http://blog.sina.com.cn/s/blog_13fd8d4b30102yzbf.htmlhttp://blog.sina.com.cn/s/blog_13fd8d4b30102yzbg.html 1.2) Hou Yuan-San (侯元三)
In a portrait gallery from the movie credited for Hou Yuan-San - "Shaolin Kung Fu" (1974), there's a portrait of Ai Chi-San,
but Ai Chi-San's name is not in the credits.
At the same time, on the poster of this movie there's Ai Chi-San's name, but no Hou Yuan-San's name.
Another movie credited for Hou Yuan-San in HKMDB is "Fixed Prize" (1969) - he has the 2nd billed role there.
Here I found kind of poster for that movie with more detailed cast:
https://tfi.openmuseum.tw/muse/digi_obj ... fc04c92f39 The 2nd billed actor's name there is Ai Chi-San, and no Hou Yuan-San's name.
In both cases every source lists only one of the names: or Hou Yuan-San or Ai Chi-San - that makes me think that they are indeed the same person.
1.3) Ai Chi-San's name - 矮仔三 - actually means “Shortie San” or "3rd Shortie" (maybe it's more correct to split it as Ai-Chi San?),
so it's not a real name, and if two other guys you mentioned - 侯元三 (Hou Yuan-San) and 侯小三 (Hou Hsia-San)(these two names seems to be proper Chinese names)
- also have the character 三 as part of the given name - this is an additional indicator, that it might be the same person.