Yes, you may add or remove numbers from a campaign at any time. When adding a new number (that is not yet enabled for SMS) you should expect SMS to be enabled within 72 hours (typically within 15 minutes).

Please note that if you remove a number from a campaign and do not reassign it to another campaign, SMS will be disabled on that number.

Awesome. I wanted to do a quick run through documenting the process before I started updating all my locations and was concerned it would be locked.

Thank you!