To dream of a will or any legal document is connected with the way in which our unconscious side can push us into taking notice of our inner needs.
To be making a will is to be making a promise to ourselves over future action.
It may also have overtones of attempting to look after those we love and care about.
To inherit from a will means that we need to look at the habits, characteristics and morals we have inherited from our ancestors. You might also like to consult the entry for inheritance.