Adding your virtual bonsai Mastercard to Google Pay/Wallet is very easy.
Go to your account to which the card you want to add is linked
Press the speech bubble under your limit: "A faster and safer way to pay! Pay everywhere with Google Pay"
Press "Add to Google Wallet"
Your card will end up in your Wallet after verification via Google. Be sure not to forget to set them as your default payment card to plant even more trees!