If she had prepared her will 'properly' (just a little online homework, or consulted with a lawyer), she would have specifically named each grandchild and why she did not want to leave them anything - and that will would have been "air tight"/not able to be challenged by the grandchildren.
Here is a very interesting resource for all of us pet folk who are a bit "long in the tooth":
"Perpetual care" » PerPETual care : who will look after your pets if you're not around? / by Lisa Rogak.
Author: Rogak, Lisa, 1962-
Edition: 1st ed.
Length: xvii, 169 p. :
Available at the River Falls, WI, Public Library through InterLibrary Loan or through Amazon.