Brian died when they were with the Maharishi and John was already sneakily seeing Yoko since they met at an Art Gallery I believe in '66, but there is a good chance that they did not meet! Apparently Yoko was writing John every day while he was in India with Cynthia.
And yes Linda was hired by Brian to take the photographs of the Beatles celebrating Sgt. Pepper after he saw her book "Rock & other four letter words".
Mind you this is all hear/say, as I was not there!!!!!