But then wouldn't the event horizon grow in relation to the new size of the BH? It would have to, otherwise you would need an infinite EH to start off with or your BH would at some stage exceed your EH.
I know that this can not be true because if it was, the universe would be mainly black hole by now but I can't seem to fathom how if something has an increase in mass (law of conservation of mass) from an external object, it does not increase in size.
My next thought would be, if gravity is...