I have a wordpress / buddpyress site, with 3000 users, who

I have a wordpress / buddpyress site, with 3000 users, who are all signed up as contributors. I am looking to convert this into a wordpress multisite, create a new blog/site, and add all 3,000 users to the new blog/site as contributors. Is there a better way to do this?

eg - mysite.com/profiles/
(wordpress installed in subfolder named profiles currently)
becomes mysite.com/profiles/newMSone

Where newMSone is a new site created by me after converted this to multisite - then need to add all previous users to the newMSone site.

Looking over the instructions on a couple of plugins here, they pretty much need to be done one email addy at a time, certainly there is a better way to do this?
I also looked at /project/add-existing-users/