XML Auto crossfeed gauge

Hi, I am hoping someone could please help me.I'm working on this plane that i'd like to have automatic fuel transfer and crossfeed control.It has a total of 6 tanks. 2 Center tanks used for forward and aft ballasting; right and left main tanks that feed the engines (the plane has 4 engines), and 2 wingtanks (right and left aux tanks).I was trying to make it so that when the planes angle of attack is over 3 degrees, the center tanks begin transferring forward. But I also need to figure out how to get the 2 tanks back level when the gear is down or when the plane is below 3 degrees... ahhh too complicated.Any ideas will be greatly appreciated!JR