Hello @MARTY53
Thanks for reaching out to our Nest Community. Don't worry, I'm here to help you share the control with your thermostat with another device.
To respond to your questions, yes, if you have another cellphone you need to sign in to the Nest App with your account, and you can control all your devices. As well, if you need to share the access with another family member, you can enter on this page and follow the steps to send an email with the access: Learn about Family Accounts.
Please feel free to keep us posted if you have any further questions, I'll be happy to help.
Best regards,
Douglas.
