Yes, I think you should gather all the census info and pull the death cert/obit.Know where they are buried?Phone for an exactly date of death and then order the cert.
1900 - 243 Grand Street, Paterson
Name: Martin Welsh [Mart Welsh] Age: 38 Birth Date: *****************Dec 1861 Birthplace: Ireland Home in 1900: Paterson Ward 7, Passaic, New Jersey Race: White Gender: Male Immigration Year: 1863  Relation to Head of House: Head Marital Status: Married Spouse's Name: Mary Welsh Marriage Year: 1884 Years Married: 16 Father's Birthplace: Ireland Mother's Birthplace: Ireland Occupation: View on Image Neighbors: View others on page Household Members: Name Age Martin Welsh 38 Mary Welsh 38 Michael Welsh 17 James Welsh 12
1905 - state census at familysearch
Name: Martin Welsh Titles and Terms: Event Type: Census Event Year: 1905 Event Place: , Passaic, New Jersey, United States Gender: Male Age: 44 Birth Year (Estimated): 1861 Family Number: 386 Page: 18 Line Number: 28 GS Film number: 1688623 Digital Folder Number: 004881597 Image Number: 00330 Household Gender Age Birthplace Martin Welsh M 44 Mary Welsh F 43 Michael Welsh M 19 James Welsh M 17