I thought that with 3 DS alums each, 1776 & the 1977 mini-series Washington: Behind Closed Doors were tied for the most number of DS folks in the cast.
Washington has Selby, Thayer & Lara.
But I forgot about Daniel Keyes in 1776, making the musical the hands down winner at 4!
Then again, some of the "traditional" soaps have cast many DS alums over the years.
Some many more than 4, I think.
David