5.1(3) 
d) The participant reserves the right to prove with reference to the lump sums stated under 5.1. that Pro+Motion GmbH incurred lower expenses and/or damages.
e) The participant can demand that a third party take part in the event in his place. Pro+Motion GmbH may object to the participation of the third party if he does not satisfy the requirements of the event or if provisions of law or public authority regulations stand in the way of his participation. In the event of a change of participant, the new third party and the original participant will be liable to Pro+Motion GmbH as joint and several debtors for the price of the event and the additional costs arising through the change.