For the marketplace seller:

Go to your affiliated suppliers list

(under Marketplace>>Browse Suppliers>>Affiliated Suppliers)

Provide your suppliers with your unique marketplace link code

(this is the same as your referral code found under Profile>>Referrals)

When a supplier uses this code they will appear in your affiliated suppliers list

You can click on the supplier from here and browse their products to add to your store.

Also, when browsing the marketplace, you can filter your search to browse the products by all your affiliated suppliers.

(under Marketplace>>Browse Products) then ( "Supplier Type" >> "Affiliated Supplier" )

For the marketplace supplier:

Contact a marketplace seller that you're interested in supplying your products to and ask for their unique marketplace link code.

When signing up as a supplier you can insert this code when prompted

(if you're not a dedicated supplier you can insert this code in Marketplace>>Settings)

This will link you to the marketplace seller and you will be available to them in their affiliated suppliers list.

From there they can easily find your products and add them to their marketplace to be sold.