Bo and Bill Winiker celebrated 50 years of music-making with a marvelous party at UpStairs on the Square this week. The brothers — Bo plays trumpet, Bill bangs on the drums — had a blast doing all their old favorites in the restaurant’s Monday Club, which was cleared of tables. Boldfacers boogying down included UpStairs owners Mary-Catherine Deibel and Deborah Hughes, Cambridge residents Peter and Katherine Thorne, the Rev. Ray Hammond and wife Gloria, former State Street CEO Marshall Carter and wife Missy Carter, Phoenix critic Lloyd Schwartz, and branding guru Stephen Simon and wife Sandra.