D'alemberte contracts with Elias to render personal nursing services for the benefit of Federica. This is an example of a third party beneficiary contract.
D'alemberte is a third party working to facilitate services between Elias and Federica. A third party beneficiary contract is still a legal contract and the third party can sue in regards to it even though they aren't the main two companies/organizations/people involved in aspects of the contract.