This sofa was purchased in Palm Springs from a Los Angeles Dealer during Modernism Week in the early part of 2001-2009. Unfortunately paperwork has been lost but the dealer said it was a Knoll sofa. It appears to look like a rare Richard Schultz sofa for Knoll and the dimensions match exactly. Note that this sofa is extremely heavy so no attempt was ever made to open it as a day bed.
Pleasse see this link: https://www.chairish.com/product/4646791/mid-century-modern-richard-schultz-convertible-sofa
Sofa Dimensions: 82” width x 31" depth x 28" height; seat height is 15"; arm height is 21"