Pointing a page to another page

Hi!

I have a template with a main navigation (Home, About, etc.) and then a sub-navigation that only shows up when there is a subpage. (Example would be, if there was Link1, Link2, and Link3 pages under the About page, those links would only show up when “About” is clicked.)

I would like that when “About” is clicked, it directs to Link1 page instead of a separate About page.

How is that possible?

Thank you!