A compound sentence is not the same as a complex one.
Yours is a complex sentence.
In order to create a compound sentence you need coordinators (but, and, or, etc). Join two simple sentences with them and there you are!
eg: Capulet's at fault for Romeo and Juliet's death but it hasn't been proved yet.
I don't think you can use 'most'. Fault is not something that can be graded.