The Firefox Home page (about:home) is not a valid url for a shortcut.

You could set your Home page to open two pages at launch and set them up differently -

How to set the home page - Set multiple pages as your home page https://support.mozilla.org/en-US/kb/how-to-set-the-home-page#w_set-multiple-pages-as-your-home-page

Home page with pipe character opens extra tabs when Firefox starts https://support.mozilla.org/en-US/kb/home-page-pipe-character-opens-extra-tabs-firefox

Nope. Sorry, it doesn't work that way. Let me look into it further for you.

If you want to ass an extra row of tiles on the Firefox Home page then you can modify this pref directly on the about:config page.

• about:config => browser.newtabpage.activity-stream.topSitesRows

You may have to close and restart Firefox.

You can open the about:config page via the location/address bar. If you get the warning page, you can click the "Accept the Risk and Continue" button.

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox