She's probably going to replace someone else in a supporting role. Either that or she's going to act in a role that has not had an actress cast in yet. Right now, I can only think of Guo Xiang- that is, if they're going to show scenes from earlier bits of the novel.
Zhang Meng updated her blog with pics of her in costume.
http://blog.sina.com.cn/s/blog_4b51a7980100b44n.html
I've got to say that the flower really makes her character look sillier instead of prettier. She would probably look better with a normal scar on her face. If they were afraid it'll make her look bad, they could always paint the scar in the shape of something nice-looking, like a colourful pattern of sorts. Sticking a flower at the side of her face just reminds me of Sha Gu playing a fool. And i agree, giving her a more decent hairstyle would make look alot more refined and pretty.
Actually looking at those pics, Zhang Meng comes across as more cute and childish as opposed to sophisticated and beautiful- a feeling i had when i first saw her pics which were mainly professional photo shoots. She actually gives off a similar vibe as He Zhuoyan- youthful, sweet and innocent.
Seeing that Zhu'er has her arm injured and is surrounded by what looks like E'mei disciples, they're probably filming the scenes where Meijue captures ZWJ and Zhu'er.
Pics of Ken Chang updated in one of the crew's blog.
http://blog.sina.com.cn/s/blog_556562e60100bxsf.html
He looks really good riding a horse. Heard he recently got into an accident on set after falling off his horse and having the latter trample on him or something. Ken has stopped filming atm and is recovering from his injuries. Poor dude.