Map Book Question - Would like Locator Map to pan for each page

I'm creating a map book and I have a locator data frame.
On each page of the map book, I'd like the locator data frame to be focused on that map grid that the main data frame is focused on.As I select the next map book page, the locator data frame should pan to the next grid square.

See the attachment. The map book data frame is showing grid 14 and the locator map is also focused on map grid 14.
What do I do to make the locator map data frame automatically focus on the correct map grid for each page?

Thanks

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