What’s the procedure for marriage registration for a US visa?

We are about to buy property from an NRI couple in Ahmedabad. The property is in the name of both the husband and wife. However, only the husband will come to India for the registry purpose. The wife has issued a special power of attorney (SPOA) for the sale of the property in her husband's name in December 2023. The SPOA has been registered before the Sub-registrar of the area in which the property is located. Now, our property agent has said that the sale deed will be sent abroad to the couple, and the wife will sign the documents. The husband will then come to India with the signed sale deed and appear before the Sub-registrar along with the POA. However, we had assumed that since the husband has the POA, he would sign on behalf of his wife. Is this legally correct?