https://suburbanguides.com — goes to a BlueHost.com page which says “There is no website configured at this address.”
https://livingston.suburbanguides.com/ — “302 Moved Temporarily” to https://livingstonguides.com/
You need (in this example) to have WordPress installed, in multi-site mode, in the folder for suburbanguides.com. It isn’t. (And that folder Must be the root of your hosting account, or must be the root of an add-on domain.)
You need (in this example) to have livingstonguides.com point to the same folder.
Then you have WordPress map livingstonguides.com to livingston.suburbanguides.com/
You also need to have your hosting company remove the redirection for livingstonguides.com. (They probably have it set up now as an add-on domain, which is not what you want.) Have livingstonguides.com point to the same place as suburbanguides.com.
You need to have your hosting company set up “WildCard DNS” for suburbanguides.com.
Tip: Don’t talk to your hosting company about “WordPress Multi-Site”, since that can trigger their “we don’t support third-party scripts” excuse. Just ask them to remove the add-on domain, and point the domain names to the right place, and set up wildcard DNS.
There are some advantages if you have one domain name for WordPress (to do all the administration), and map suburbanguides.com and livingstonguides.com. Because the prices were lower, I used a .info for WordPress:
— your-other-domain.info in /public_html for WordPress,
— suburbanguides.com points to the same folder,
— livingstonguides.com points to the same folder
I give much more detail in https://lcblog.lernerconsult.com/2012-wordpress-3-multi-site-installation-existing-web-sites/