Change vendor usergroup when approved

Hi

I have a question about the vendor registration proces. I created a shop where every user can become a vendor. When the user registers as a vendor the registration has to be approved by enabling his (vendor) account.

A user has the usergroup 'registered'. The 'usergroup on registration' setting in HikaMarket is 'vendor'. When the vendor registration is approved the usergroup stays on registered. Can the usergroup change automatically when approving the vendor registration?

Regards
Wouter