Is the marriage contract considered valid if the guardian did not specify the name of the sister during the offer, contenting himself with saying, "I marry my sister to your client," knowing that the agent mentioned the wife's name in the acceptance, and the witnesses were aware of the engagement beforehand?

So long as the contracting parties and the witnesses know the wife intended by the contract, then the contract is valid, and the guardian's failure to mention the wife's name does not cause harm. Some scholars have stipulated the validity of the contract in this situation, as long as the spouses agreed upon one of the two daughters and intended her at the time of the contract, and the witnesses were aware of her.

And since the dowry was paid before the contract, the marriage is valid with this dowry, and the failure to write it in full in the document does not cause harm.