[SOLVED] Import members from 1.5 to 1.7/2.5

Hi
I have a Joomla 1.5 site which has signed up several hundred members over 6 months. Community Builder is not installed. Members have been signing up through K2 login module. I am redesigning the site, and will relaunch in a few weeks on Joomla 2.5, using CB and CB Subs to register members. Currently members are able to register with one name, eg "Joey", plus a username and password, although some users have given their complete name anyway. I will be requiring members on the new site to register with a first and last name, plus the username.
I am wondering what the best policy would be here. I have tried importing the existing username list successfully to a test 1.7 Joomla site with CB installed, although not CB Subs. I could newsletter/email existing members and ask them to upgrade their details within a specified time, once the new site is online? Or I could require a re-registration? I am obviously concerned that the different registration history, particularly with members who have only entered a single name, will cause conflicts in the future using CBSubs.
Thanks.

CB does not have a user import feature. For that you'll need to use CB Juice. CBSubs import is for importing subscriptions to existing users; it will not import actual CB users.

Hi
I don't think I explained myself very well. Importing/exporting users in not the actual issue, as I am using ARRA import/export to do this, and it seems to be fine.
All I am concerned about is whether users who have just registered with a single name, instead of the firstname/lastname which I will require on the new version of the site, will cause conflicts in the database etc, once they are imported? I am reluctant to exclude these users from the new site, and could give them a chance to update their registration details, but I don't want to cause any technical issues in trying to do this.

No, single name won't cause a problem. Joomla doesn't actually have first/middle/last as that's specific to CB and all CB does is split the name into 3 segments. So providing single name is perfectly fine.

Thank you very! That's very clear, and what I needed to know.