vb Usergroups

[XYZ500]

I want to make some changes to usergroups and permissions.

I had four usergroups. Newbies > Members > Senior members > VIP Members.

I want to change to Newbies > Members > Senior members.

I edited the promotions too. Now how do I shift the VIP members to Senior members group? When I try to delete VIP members usergroup it says "All members of this usergroup will revert to the Newbie group."

As I mentioned I edited the promotions too, so will the system adjust the users itself and allocate the current users according to the new promotion settings? E.g, I changed promotions from Newbies to Members from 10 posts to 25 posts. So the users that have more than 10 posts were Members, but according to the new promotion settings users with even 24 posts should be in Newbies. So the users that have less than 25 posts, will they automatically be moved back to Newbies or do I have to do something for that?