Yes its possible Use your ragnarok database for IPB login.
1. Disable forum registrations so that the only way to register is via your server’s registration.(There a setting to redirect IPB’s registration link to your CP’s registration page)
2. Use IPB’s built in merge account feature to merge your users’ existing account to the new account.
3. Disable IPB’s internal login. Using two databases would be messy, really messy don’t even try!
Credits to: clydelion
