Rebecca Hiller was hired as a Consultant by a non-governmental organization ("NGO") to advise how best to assist a Small Island Nation that had been devastated by an earthquake and a tsunami. In her consulting contract with the NGO, there was an arbitration clause. The NGO had also hired a Project Manager to manage rescue and reconstruction activities in the Small Island Nation. In its contract with the Project Manager, the NGO included an identical arbitration clause.

Ms. Hiller was told that she should take instruction from and report to the Project Manager in carrying out her duties under her contract with the NGO. At some point a dispute arose, mainly between Ms. Hiller and the Project Manager. Ms. Hiller commenced an arbitration against the NGO and the Project Manager. The Project Manager asserted that he could not be a party to the arbitration because he had never signed an arbitration agreement with Ms. Hiller.

You are the sole arbitrator. What alternative legal theories about non-signatories might you rely on to find that the Project Manager should be required to arbitrate? Please explain each possible choice and decide which theory would best support a decision to require this non-signatory to arbitrate.