What is the ruling on delivering a trust to a person to convey it to a girl at the request of the owner of the trust, knowing that the relationship between the owner of the trust and the girl is illicit, and does the ruling differ if the one delivering the trust is already in contact with the girl?

You must deliver the trust to its owner's agent, for the agent stands in the place of the principal, and his actions are considered valid. A Muslim is commanded to deliver trusts to their rightful owners, as Allah Almighty says: "Indeed, Allah commands you to render trusts to whom they are due," and the hadith: "Deliver the trust to the one who entrusted you." The fact that the agent or the principal might engage in unlawful communication with the girl does not preclude the obligation to deliver the trust. In such a case, you should remind them of the unlawfulness of that, as an act of sincere advice and enjoining good, and it is not permissible to refuse to deliver the trust for that reason.