Sorry I don't have any details on your specific family. In 1930 Brooke Co, WV there was a Tillie Ambrose, b 1917. WV has many vital records available online, so you might find marriage record there. There is a death record for Tillie V. McAllister, b 1916 & died 9 Dec 1978 in Detroit, Wayne Co, MI. She is buried at Sheldon Cem, Canton, MI.
Wallace was stangely elusive in census records (also checked for Hugh). If he was born 1918, he should appear in 1920, 1930, & 1940. The only close match was Wallace McAllister in 1945 Florida state census. He resided in Bay Co, b ca 1917 in TN. There were a few Wallace McAllisters scattered around the country in early 1900's, but none that closely matched your details.
Have you tried sending a query to [www.clanmcalister.org
]? They have a large database of McAllisters (all spellings) going back to 1700's & 1800's.
This isn't a lot of detail, but at least might give you a few more placed to look. Good luck on your search!