Thank you so much, Annette! I took your advice about the siblings and found that William had 5: James (1832), Ellen (1835), Catherine (1837), Christopher (1839) and Laurence (1842). And Catherine Dalton died much later than I originally thought: in 1861 (not 1836.)
I also used the telephone directory to find Dalton's and Hurley's with whom I can connect. (I even found some on Facebook!)
I really appreciate your efforts to help me and your sound advice.