Job Recruitment Website - Property management - Is the signature of the property project manager valid?

Is the signature of the property project manager valid?

Effective.

Because he represents all the property, his signature is valid.

The other project manager should issue a power of attorney, and the official seal of the other company and the legal person seal of their boss on your contract are enough. Then the legal relationship is the relationship between your company and the company, and the project manager is only an agent, exercising his functions and powers within the scope authorized by the legal person.