To add gift cards from other stores, you’ll want to find their gift card page and use the “Add to Babylist” button to add it to your registry. Here's an example.
Leave the quantity blank (remove the 1) and add a zero to the price box. That makes it so there’s no limit to how many gift cards can be reserved and they can choose the amount they want to give.
If you’re adding an e-gift card that has to be emailed to you, make sure you include your email address in the note box so gift-givers know where to send it.