The use of leaves is up to you - what meaning do you draw for them? Leaves can mean that you're seeing this as a circle of life - that dying is simply a shift to a new form of being. Do you believe in reincarnation? You might try some fresh leaves to show that you believe they have moved into another form. You could include decaying leaves, as they are meant to show death or dying, but I prefer to use more positive imagery, even if it is meant to be about death. You are trying to keep their memories alive. Ask yourself what the leaves would symbolize to you - it doesn't have to follow the traditional beliefs. This is a very personal thing, so consider what you believe.