What OS is on the phone? Which watch are you using? What OS are on the watches? What cell plan do you have?
Yes, you can pair 2 or more non-LTE enabled watches with the same Apple Account to 1 phone (people do this all the time, one watch for sleeping, one for daytime). You can do multiple watches for up to 6 people on one iphone with a single cell plan using the Family Plan. The second option requires iOS14, WatchOS7 and Series 7 or Series SE watches with LTE capabilities plus monthly charges per watch. I suspect that Verizon has serious limitations on the watches.