tweak few codes in a buddypress onepage extension

i'm using a tiny plugin to add a custom user role to buddypress groups members and remove it when they leave the group , i need to tweak the code to add the role to group admins , when the user be promoted to admin he get the role .. and he lose the role when he be demoted to mod or member , or be removed or banned of the group. please accept only if you're familiar with buddypress hooks