The executor is the one who has control over the memorial, so with Brandi's friend, if there had been a different executor, the problem would have been avoided. You should specify that in your will.
You'd need to check your local requirements, but a will does not have to be drafted or witnessed by a lawyer in many jurisdictions, including the one I live in. If you do get a form for a will, make sure it is specific to your jurisdiction. I'd check bookstores before looking online, just because they're more likely to actually be valid where you live.
Dennis