You haven't explained why you are waiting on your cousin.It is against the law to withhold a Will from being filed in probate. A probate should be filed as soon after the death as possible. If you are an heir at law then you should visit the court and see about filing yourself. The title to the real property cannot pass to the heirs until the estate is probated and you should be concerned that the property is not insured against loss and that the taxes are not being paid. Take that initiative yourself. The property should be sold and the proceeds distributed according to the Will or the laws of intestacy if there is no Will.
Depends on what side of the family your cousin and great-grandfather are on... If your cousin is not descended fro your great grandfather, they are not related. If your cousin is descended from your great-grandfather, and your cousin is not a "removed cousin" as in second cousin, once removed, etc., then your cousin is your great grandfather's great grandchild, as are you.
Your grandfather's first cousin is your first cousin, twice removed. Your grandfather's second cousin is your second cousin, twice removed. Your grandfather's third cousin is your third cousin, twice removed. The relationship possibilities become more complex if you are talking about your grandfather's cousins who are once (or more) removed.
Your grandfather's first cousin is your first cousin, twice removed. His second cousin is your second cousin, twice removed.
Your grandfather's first cousin is your first cousin, twice removed.
Your grandfather's first cousin in your first cousin, twice removed.
Your grandfather's first cousin is your first cousin, twice removed. His second cousin is your second cousin, twice removed.
The son of your grandfather's First Cousin is your parent's Second Cousin and your Second Cousin, once removed. The grandson of your grandfather's First Cousin is your parent's Second Cousin, once removed, and your Third Cousin.
Your great grandfather's nephew was your grandfather's first cousin. You are two generations removed from your grandfather and his cousin. Therefore you and your great grandfather's nephew are first cousins, twice removed.
Your grandfather's nephew is your parent's first cousin. Your grandfather's nephew's daughter is your second cousin.
Your grandfather's first cousin's niece could be:your motheryour second cousinsomeone you are not related to (for a niece through marriage to spouse)
Your great grandfather's nephew was your grandfather's first cousin. You are two generations removed from your grandfather and his cousin. Therefore you and your great grandfather's nephew are first cousins, twice removed.
You could easily be unrelated to your grandfather's cousin's second cousin.If the two of you are descended from a common ancestor, the closest relationship possible between the two of you is second cousin, twice removed.If your grandfather's cousin is not his first cousin, then the relationship is more distant.