Did you get the inherited real estate license? If it already exists, the spouse of the obligee who does not appear on the real estate license has nothing to do with the formalities of selling the house (that is, he is not required to be present to sign the sales contract, because he is neither qualified to sell the house nor needs his consent-at least in Shanghai).
There is something wrong with your statement: first, you said "online signing is needed, but people can't contact you", and then you said "I signed a house sales contract with the buyer before". Are the two house sales contracts before and after ........... clearly stated? Strictly speaking, there is only one sales contract! After the contract online signing system is implemented, only the online signing contract will take effect.