Is it possible for them to get visit visa for 30 days? and i dont want to get it extended.

Hi, Ali! If they want to get tourist entry permit, they have to join a travel group organized by a qualified travel agency. So I would suggest they apply for the S2 type by providing a photocopy of your passport and residence permit in China. The allowed stay duration of S2 type is usually longer than that of L type. It’s possible that the duration can be 30 days.