Browse to the left navigation where you want to add a link to an existing RedDot page
Open the OpenPage RedDot that corresponds to the left navigation
Select the MultiLink RedDot that corresponds to the left navigation
Select Connect to an Existing Page
Search for the existing page you want to link to (recommend using headline field and searching for headline of page)
Select the page name hyperlink that corresponds to the existing RedDot page you want to connect to (if you need to preview the page before selecting it, click on the 'Preview' hyperlink)