Adding new Customers in bulk

-- HikaShop version -- : 2.6.3
-- Joomla version -- : 3.5.1
-- PHP version -- : 5.4
-- Browser(s) name and version -- : chrome
-- Error-message(debug-mod must be tuned on) -- : n/a

I have created a wholesale area for our shop. It works great and my client is pretty happy with it.

However, there is one thing I am unclear about. The client has provided me with a list of wholesale customers to enter into Joomla and the store.

I know there is an extension for joomla that can create new users in bulk. At least I remember using it. My question is how do I also make sure these new users (assigned to the "wholesale" group) get registered as customers and have their address entered in Hikashop?

Is there a way to add customers in bulk?

Thank you very much for the reply and the instructions.

If you don't mind I have a few additional questions. Please keep in mind this is a working shop so I have to try to minimize downtime and especially minimize outages, errors, etc. It also means I have already Retail Customers in the shop that should remain unaffected by this.:

1) Is there a way to import new users and set their Wholesale user group during import?

2) If #1 is negative, what is the best strategy to use to process the new Wholesale Users so that I don't mistakenly assign the Wholesale User Group to any of the existing customers/users?

3) Thank you for the "Check Database" hint. I knew about that but I forgot. The issue that remains once I import the Ws users, I change their user group and finally Check Database, is importing their addresses. How would I go about doing that?

4) Lastly, I would like to set all the new Wholesale users so that they need to change their password as soon as they log in for the first time. Do you know if that is possible?

Thank you.