Secondary to Primary usergroup promotion

[Alfacorse]

I have tried searching the forum for this and found nothing so far. Apologies if this has been requested already!!

I am looking for a cron script that I can schedule every 15mins or so to perform the following:

If user is a member of usergroup "Registered" has secondary membership of usergroup "Member" then make their primary usergroup "Member" and remove secondary usergroup permission.

the reason for this is that my mods control peoples membership to the secondary group and the associated permissions via a Public Joinable Group. However I want to restrict their usage of hacks like Shoutbox and VBArcade, which only look at a users primary group setting.

I have looked at promotions and can't get this to work how I want it I know this must be simple, but I am just a lowly webmaster and not a programmer :'(

"Help me Obi Wan, You're my only hope"

Can't be that hard can it :disappointed:

Could someone at least let me know how a primary and secondary user group is registered? I tried looking at the subscriptions code to get it to work along that basis, but failed miserably :'(