You can grant any other Gridset user access to your grid set by simply adding their email address to the Sharing list (in the Use section). After adding a user, he or she will then be able to sign in and see your set in their list. They will also be able to edit, save, and access all of the assets for the grid set. Only the set owner can change the Sharing.
Transferring Ownership of a Grid Set
You can transfer the ownership of a grid set to anyone on your access list. Ownership gives you the ability to control Sharing for a grid set. You just need to hover over the user’s name and click Transfer. You will be prompted to confirm the transfer, and after confirmation you will be returned to the set’s Edit screen. After transfer, you will no longer have access to the the Sharing screen for that set.