EUOSHA/2021/OP/F/SE/0142  and operational management. The group leader will have full authority to bind the group and each of its  members during contract execution. If the joint tender is successful, the  contracting authority  shall sign  the contract with the group leader, authorised by the other members to sign the contract on their behalf  via power of attorney drawn up in the model attached in  Annex VIII .  Changes in the composition of the group during the procurement procedure (after the submission  deadline and before contract signature) shall lead to rejection of the tender except in the case of a  merger or takeover of a member of the group (universal succession), provided that the new entity has  access to procurement (see  section 3.2 ) and is not in an exclusion situation (see  section 4.1 ).  In any case, the selection criteria must still be fulfilled by the group, and the terms of the originally  submitted tender may not be altered substantially, i.e. all the tasks assigned to the former entity must  be taken over by the new entity member of the group; the change must not make the tender non- compliant with the tender specifications; and the evaluation of the award criteria of the originally  submitted tender may not be modified.  Subcontracting is the situation where the contractor enters into legal commitments with other economic  operators that will perform part of the contract on its behalf. The contractor retains full liability towards  the  contracting authority  for performance of the contract as a whole. The following shall not be considered subcontracting: The persons mentioned in points (a), (b), (c) and (d) above will be considered ‘personnel’ of the  contractor as defined in the contract.  All contractual tasks may be subcontracted unless the  technical specifications  expressly reserve the  execution of certain critical tasks to the sole tenderer itself, or, in the case of a joint tender, to a member  of the group.  43  3.4.2  Subcontracting  f)  Performance of part of the contract by members of an EEIG (European Economic Interest  Grouping), when the EEIG is itself a contractor or a group member.  e) Use of suppliers and/or transporters by the contractor in order to perform the contract at  the place of performance, unless the economic activities of the suppliers and/or the  transporting services are within the subject of this call for tender (see  Chapter 2 ). d) Use of staff without employment contract (‘self-employed persons working for the  contractor’), without the tasks of the self-employed persons being particular well-defined  parts of the contract.  c)  Use of workers temporarily transferred to the contractor from an undertaking established  outside the territory of a Member State and that belongs to the same group (‘intra-corporate  transfer’ as defined by Article 3, (b) of Directive 2014/66/EU on the conditions of entry and  residence of third-country nationals in the framework of an intra-corporate transfer).  b) Use of workers hired out to the contractor by a temporary employment undertaking or  placement agency established in a Member State (‘hiring out of workers’ as defined by  Article 1, 3(c) of Directive 96/71/EC concerning the posting of workers in the framework of  the provision of services).  a) Use of workers posted to the contractor by another company owned by the same group  and established in a Member State (‘intra-group posting’ as defined by Article 1, 3(b) of  Directive 96/71/EC concerning the posting of workers in the framework of the provision of  services). 