Su Li

There's one very minor character mentioned on the classlist in the sorting ceremony in the 1st book named Su Li. Not much is known about her other than she was sorted in to Ravenclaw and was in the same year as Harry. I'm interested in playing her because I'd like to have an adult multi-character that's very different from my current. I noticed that she wasn't on the list of free & taken canon characters.

My question is: Do I need to apply for her as if she were a canon character?

Hey there!  I did a bit of research on her, and yes you would have to apply for her.  I do suggest taking what hp-lexicon has to say about her into mind when doing so though. 

Su Li has a rather bland name that really only indicates that the character is ancestrally Chinese. “Su” is a common Chinese name meaning “pure,” so it is roughly equivalent to “Katharine.” “Li” is one of the most common Chinese surnames and it is said to mean “plum tree.” This character may have been the prototype of Cho Chang, hence axed for all practical purposes once JKR decided to make her glamour girl unattainable by placing her in the year above Harry.

Assuming that Su is still a real character, we know that she is a half-blood and ethnically Chinese. The Chinese community in Britain is small (about 0.5% of the population), well-integrated and well-liked. Su’s grandparents would have arrived in Britain around 1960 and set up Chinese restaurants in London (the Muggle grandparents in an area such as Southwark, the wizards in Diagon Alley). Su’s parents may have inherited the restaurant business, but they would speak better English. Since a wizarding family who spoke good English might prefer the company of Anglo-Saxon wizards to that of Chinese Muggles, Su might not identify very strongly with the Chinese community; she would probably speak some Chinese but prefer English.