Can a grandchild request an advance on inheritance from a living grandparent's executor or POA?

Here's a really interesting question from a reader. It deals with asking for an advance on an inheritance from an older relative, and who might be allowed to make that decision. Read on for the question and my comments.

"A grandchild is looking for a advance on the inheritance from their living (90 yr old) grandparent. Is this legal? I believe grandma's executor will be asked. And he may be