There are some who claim there is evidence that "Albert Einstein" is really a shortcut/brand name for the husband-and-wife team comprising Albert and his first wife Mileva Maric; I read somewhere that they decided to put only his name on the papers to make it more likely that he may get a permanent job. His wife and fellow student certainly was intellectually involved, and Albert wrote to his wife once: "How happy I am to have found in you an equal creature". She was smart yet failed her final exams. (He left her for his own cousin.)
General relativity was not produced in isolation, there were a number of other big names in mathematics and physics at the time trying to find a relativistic theory of gravitation. Einstein will have been discussing with the other physicists and been familiar with their work.
