My grandmother had around 35 grandchildren and 10 greatgrandchildren when she passed. Notifying everyone wasn't hard. One child called a couple of their siblings those called a couple more siblings and/or their kids. Their kids told their kids. Then the inlaws called their sides of the family. Everyone was notified in a few hours. It wasn't even organized beforehand, these things happen in an ad hoc manner. No one person even had the contact information for even half of the others.
My grandmother had around 35 grandchildren and 10 greatgrandchildren when she passed. Notifying everyone wasn't hard. One child called a couple of their siblings those called a couple more siblings and/or their kids. Their kids told their kids. Then the inlaws called their sides of the family. Everyone was notified in a few hours. It wasn't even organized beforehand, these things happen in an ad hoc manner. No one person even had the contact information for even half of the others.