|P.S. We miss John Candy! R.I.P.|
If you inherited ... Your next step is research and documentation. If you and your brother inherited your mother's share, you will have some paperwork ahead of you. First, you need to determine the sources of the royalties. Then, you must contact the sources and provide them with appropriate documentation proving that you are entitled to the payments. This may require providing a death certificate as well as estate or probate documents (state laws differ) demonstrating you are the heirs. Most likely you will have to contact your mother's siblings.
As for the name and likeness ... Making money off your grandfather's name and likeness (from endorsements, etc.) depends on the contracts he signed while alive, the contracts signed after his death and state "right of publicity" laws -- some states provide for post-death rights, others do not. Again more research is needed. Possibly, somebody is coordinating these endorsements, and that most likely is one of your aunts or uncles, or someone appointed by them to manage these endorsements. Research is needed!