Adding an account to a Pro account

btw, should I create the user first as a basic user and then add them to the account?  Or???  I don't know why it seems hard to find this info.

There are a couple of ways to accomplish this, depending on your needs. 

One method is along the lines of what you are asking about, which would be setting up an Alternative Host. This requires a 2nd licensed user on the account, which you can designate as an alternative that has the ability to start and host your meetings. You can invite an existing user, or create a new user from scratch, but both would be done through the Users page under User management. As I mentioned though, this does require the 2nd user to be licensed, which means you would have to purchase (or increase your number of licenses on your current subscription) and assign that license to the user. 

Another method is to share your Host Key with those who need access, as described in this post: "Alternate Meeting Hosts" Keep in mind, this method does require disabling some security features for those meetings and sharing what is essentially your Zoom profile's pin number (Host Key). 

Hope that helps and please make sure to mark the solution as accepted if this information is what you needed.