Prevost family in Michigan

Hi:)

I'm helping a friend research her Prevost line, and I'm wondering if there is another spelling I shoudl search for, we have David Prevost on the SSDI, and his second wife, but can't find David in the census records, he should be there in 1920 and 1930, but I can't find him. Any other clues about the Prevost family would be appreciated. :)

Kate