Jimmy Reid, 70, toured America with Brubeck and attended jazz festivals in Europe as well as his home city, but led a quiet life in his later years.
His family plan to sell off his music collection, with a donation going to Glasgow International Jazz Festival.
"We went through his address books to find contact details for friends, but most of the numbers were old," said Sarah Clarke Wood, who is married to Mr Reid's nephew Graham.
"The night before the funeral we managed to get in touch with friends in London but it was too late by then for them to get to Glasgow."
Among the friends she did manage to trace was Glasgow writer James Kelman, who shared a house with Mr Reid in London in the 1960s.
Ms Wood said: "There's a classic story about Dave Brubeck doing a gig and there were questions from the audience. He pointed to where Jimmy was sitting and said, 'Ask that guy, he knows all about my life'."
Mr Reid lived in Pollokshaws and worked for HMRC.