There is family tree for William on FamilySearch, interesting in that it has details for children, but of course it has the incorrect parents from his death registration.
The parish register for the Cathedral in Chicago, where he married Lizzie Hughes in February 1890 only shows the names of the parties and a single witness. Not even as much as a typical (poor) Irish parish register, which would normally have two witnesses. IIRC, Cook Co. marriage licenses also only show the names of the parties - no parents names.