Is an 'urfi' marriage valid if it was conducted in the presence of one witness, and the second witness appointed the first witness as his proxy, and the contract was signed on two different days?

If the marriage contract is concluded without a guardian (wali), it is invalid according to the majority of scholars. Similarly, if it is concluded in the presence of only one witness, it is invalid. As for one witness delegating another to testify, that is not valid. If the contract is concluded with an offer and acceptance between the guardian and the groom in the presence of only one witness, the contract is invalid according to the majority, contrary to the Maliki school who do not stipulate the presence of two witnesses at the time of the contract, but rather require attestation before consummation. The more cautious approach is to renew the contract with its pillars and conditions, and to register it in the courts to protect rights.