I found some rumors on the internet regarding Stückelbergs manuscript and it's role for the development of QED. In a comment on here somebody writes:
Crease and Mann say in their book The Second Creation (revised edition, Rutgers 1996) (page 143) that Stueckelberg “… in the army, was almost totally isolated from physics. Nonetheless, he apparently wrote up a lengthy paper – in English, for once – that outlined a complete and correct description of the renormalization procedure for quantum electrodynamics. Sometime in 1942 or 1943, he apparently mailed it to the Physical Review. It was rejected. “They said it was not a paper, it was a program, an outline, a proposal,” Stueckelberg remembered. … Stueckelberg was not a bitter man. … We asked if he had the manuscript, which would help him establish priority. “I never cared much about that question,” he replied. “I don’t know what happened to the original copy. I lost it, it completely disappeared. …”.
On this page while here I find the quote
Via anonymous email somebody informed me about the following anecdote: After Feynman won the Nobel Prize, Schwinger called him up and asked: "Now are you going to give Stueckelberg his notes back?" (The unknown author: This is anecdotal from a friend who is a theoretical physicist living in Boston whom I have known for 35 years. He told me this several years ago and I believe it to be true.)
And finally here Richard Bentley admits
I was the person who sent you an email some time ago regarding a physicist who called Feynman after he won the Nobel prize to ask him if he would now give Stueckelberg’s notes back. I was incorrect in the identification. My understanding now is that it was Sidney Coleman.
So my question is this: As implied by these quotes, could it really be that Stueckelbergs manuscript in fact disappeared, because Feynman got hold of it, never returned it and used it to develop QED? And could it be that this was in fact an open secret in the physics community, so that Sidney Coleman could have known about this and Murray Gell-Mann apparently even referred to Feynman diagrams as “Stueckelberg diagrams”?