UPDATE: Joe Estevez tells TMZ the guy claiming to be his manager is just an acquaintance and does not rep him at all. He calls the whole thing a "total and complete fabrication."

Charlie Sheen's uncle, Joe Estevez, is looking to cash in on the problems of his nephew ... by lobbying for Charlie's role on "Two and a Half Men" while Charlie is in rehab.

TMZ has obtained a letter sent from Joe's manager to Chuck Lorre, the creator and EP of "Men." The letter describes Joe as "by far the funniest of the Sheen & Estevez clan."