If you are building a site that is replacing an old site, you will need to Add a Custom Field to each page on your site to avoid broken links. Once this is done, and your new site is live, if a user has bookmarked a page on the old site, they will be routed to the correct page on the new site.
To add this Custom Field to your page, visit the old site and copy the web address of the old page.
Go to the replacement page in WordPress and scroll down and look for the Custom Fields area.
Under Name, type: wfu_previous_url
If there is a dropdown menu instead of a blank, select wfu_previous_url
Under Value, enter the link to the old site that corresponds to the replacement page on the new site.
You can enter as many Previous URLs as you need to on a particular page.
Note: If there is a page on the old site that does not have a corresponding page on the new site, add it as a Previous URL to the Home page of the new site. Also, when adding the old links, be sure to add the directory link, and the link to the index page, as shown below.