Yes. You can own as many Haystack cards as you want and choose which ones to share.
To add another Haystack card:
Open the app to your list of cards and scroll up above your existing Haystack card.
Tap 'Create another card'
Type in a new email address for the new card you want to add and follow the prompts
Your new card will appear and we'll send you an email to confirm that it belongs to you.
Note: Each card needs a separate email address. If you want to create more than one card for the same email address and you're using Gmail as your email provider, then you can use the 'Gmail '+' trick'. Otherwise, you are welcome to contact us - in some cases we allow multiple cards using the same email address (paid plans only).