neHi @Catherine_03732. Thanks for reaching out to us here on 3Community, and yes, you can add a second mobile number to your account. To add a second number, all you need to do is log into your My3 account. Once you're logged in, head to the online shop and select the device that you are looking for. Once you select the device, you'll see the option 'Add To Your Account', select it and complete the purchase.
Any question let me know.
