Rainboe,
If you new anything about the Airline Industry you would know that the aircraft are effectively impounded until the airline/lessors pay any outstanding fees at the airport they are at!
Once the fees are paid, the aircraft are free to move. The XL aircraft in MAN for instance had tractors parked behind them, not to prevent them from moving, but as a symbolic stance. In this instance, the lessors have paid the fees to get their aircraft back. They will then chase the fees with the liquidation company. The aircraft which are owned by the lessors carry the debt, and until this debt is cleared the aircraft is used as a pawn in a very intricate damge limitation exercise.....