It could be that Don Rosa was a guest or exhibitor at Lucca Comics. Or perhaps his comics were showcased or sold there. But I don't have exact details.
Hard to say for sure. Maybe Lucca Comics hosted events related to Don Rosa's comics, or maybe there's some licensing deal between them. Without more context, it's difficult to be precise.
Not sure. Maybe they collaborated on a project or Don Rosa's works were featured at Lucca Comics.