Supporter - Modify it to give the users a default credit of X blogs on sign up

Hello I would like to know which clause or function or what I would have to add/ edit or so to have the supporter plugin in which when they sign up for a blog and pay the supporter dues they get money right away! so when the purchase the premium membership they directly get the x blogs which are set and do not have to go into bulk upgrades to purchase credits!

What I have done is modified it a bit to hide the option to sign up for a free blog. they have to pay before they can go into the dashboard.

so when they will sign up they automatically receive credits for 50 blogs and can bulk upgrade later on for more blogs!