I don't recall anything about there being multiple dinners. It may have been brought up in Blood Right, but Arianna's involvement was definitely brought up at the end of Changes.
I would have to find the exact quote in Changes, but I am pretty sure it was more than one dinner, which
would make sense when you think about it. Margaret was with if not married to Raith for several
years, Thomas was six or seven when she left him. Not saying they were happy affairs but unless
Eb wanted to cut himself of totally from his daughter and she, him, that would be one way to keep
the connection going.