I haven't played Europa Universalis in a long time, so if there was a change with BT on colonies, I wouldn't know. However, when I placed my second additional colony (4x maintenace) in a 6 BT colony, I experienced a deficit, but when my second aditional colony was 2 BT, I stayed above water. I consider the penalty being determined by order of colony creation arbitrary. Order should have nothing to do with it. Order is meaningless. Because I created a colony first doesn't make it less expensive. Instead, it should be determined by the presence of a colonist, which the player can control.