I am so sorry for your loss.  There are many forms that you will have to sign during the course of the Probate and more that will be filed during the course of the Probate that the Court will require.  Some to allow your brother to be appointed as the Executor of the Will, which is what yu may be getting in the mail.   It is probably a waiver to allow him to be appointed.  But I think that the best thing for you to do is to wait and see what you are getting served with and then to speak with an attorney on your behalf to review the documents and let you know what is going on, especially if you do not trust your brother.  It may be money well spent for your peace of mind.  Good luck.