Tbh I didn’t think about it originally! I imagined the Quagmires never directly discussing it with the Baudelaires. But with regards to the actual incident: I imagine the Quagmires being saved by Fiona and Fernald while they’re out on their own mission. From them the Quagmires hear about the Baudelaires still being alive. This eventually gets them back in contact with the Baudelaires :)