Once your dad's ship gets destroyed.. you are toast.
Go after the bombers that are goign after your dads ship, and the Rebel trasports. Try to disable, or wound the bombers enuf so they fly back home.
You are just trying to make sure your dad stays alive long enuf for the otehr transports leave.
YOu cnnot stop your dada from dying, but you can delay it. Once he dies, the GUNS show up, and the ATRs go after the station