Need to Alter the way Membership plugin is working

Hi,
Attached with this post are 3 screenshots on which my question is based. As u see that the process is divided in 3 steps. 1st steps fetches all the info, 2nd step sets the membership level and the 3rd step completes the registration.
I want the second step of setting membership to occur in the first step itself based on the value of account type field in that step.