There is no such compound surname in the hundred surnames. The characteristic of compound surname is that two Chinese characters form a surname, which is a whole. Some compound surnames are separated into two single surnames. For example, Sima is a compound surname, while Si and Ma are both single surnames after separation, but these two single surnames have nothing to do with Sima.

Li and Su are both single surnames, and the compound surnames are inherited from history and family lineage. No one can take whatever surnames they want, let alone combine them at will. And every family has a family tree, and which generation is the first generation. You can't combine two single surnames into compound surnames, even if they are combined, they are not surnames. For example, if the parents are named Zhao and Qian respectively and their children are named Facai, then the person named Facai will still be named Zhao instead of Qian.