The easiest way to link the auction to other products is through the welcome message. Use this space to hyperlink to other campaign you'd like to feature. To set it up, head to Settings >

Welcome message, then type your greeting and hyperlink the link to the the other campaign.

How it will look:

Where to create the welcome message:

You do have the ability to connect impact items from an Impact Item campaign to an Auction campaign. Find out more about that here.