Bridge for users between php fusion 7 and phpbb3

The job is for a small gamming guild website fleet187 to bridge the PhP Fusion 7 with PhPbb3 so that the primary login / registration will occur with PhP Fusion 7 and when user selects to go to the forum area (PhPbb 3) no login will be necessary it will have the same credentials / user information as registered in PhP Fusion 7 to post and use the PhPBB 3 boards.