Think of it in this sappy light: you tend to agree with those who are closest to you (family and friends), right?
Awww. Ain't love grand?
Well, compound subjects and verbs are no different. The verb agrees with its best buddy: the one that it's closest to.
In this example, is agrees with Willy because it's the closest.
Here, has agrees with Connor because it's the word that's nearest the verb.
In this sentence, have agrees with friends because it's closest.