Ruling 2386
One individual can be an agent for both parties to say the formula of the marriage contract, be it temporary or permanent. A man can be an agent for the woman to marry her to himself, both in a temporary marriage and a permanent one. However, the recommended precaution (al‑iḥtiyāṭ al‑mustaḥabb) is that the formula should be said by two individuals.
-Ayatullah Sistani, English Islamic Laws 4th Edition Page 421