Is the theory that before the assassination - at some time on some occasion and in some way - the conspirators who framed Oswald for the shooting obtained Oswald's rifle, his camera, access to the backyard at the Neely Street residence, and copies of the two radical publications that are seen in the photo?
Then these unnamed conspirators took a photo. Actually several. They then pasted a - obvious to conspiracy believers but not photographic experts - head shot of Oswald onto the staged photos.
Then they made three - not one, mind you - but three faked/staged photos and planted them. Including a negative.
Moreover, they got the DeMohrsenschildts to lie about being given one of the photos by the Oswalds. And, of course, got Marina to lie about taking them. But there's one more, the handwriting on the back of their photo given to the DeMohrenschildts was identified as belonging to Lee Oswald. But that is wrong too.
And they were so good at this fakery that photographic experts using microscopic analysis of the originals and the negative (matching it to the camera) were unable to discover this fakery. Even modern analysis, some 50 years later, using digital techniques (see for example Harry Farid and his team's work on this) is unable to discover these alterations.
This is simply not believable. Or doable. Not to me.
This farfetched explanation is a classic example of how the conspiracy believers believe literally anything and everything in order to make their conspiracy work. It is simply impossible to do all of the above. But never mind, "they" just did and, hey lone assassin fools, prove "they" didn't.