I received a request to contribute a book chapter about a month ago, which I turned down. This was from a university in another country, and from someone I have personally met.
Today, my own supervisor asked me to contribute a similar chapter to a book which she has been asked to be an editor of.
Given that the two requests happened in a relatively short time, and the reason I gave for declining the former request might still stand, would there be a problem if I accept the latter request, when I have declined the former?