Yes, any multiple contractors can upgrade different parts of your smart home but only one contractor may update your Devicebook Smart Home at a time.
If you have two contractors that want to make improvements to different features in your smart home, you should do the following:
1. Accept the request from one of the contractors to modify your smart home. That contractor will then be able to modify and upgrade your Devicebook Smart Home.
2. When that contractor has made any necessary changes, and set up the required devices, they'll transfer the smart home back to you.
3. Accept the request from the second contractor to modify your smart home. The second contractor will then be able to modify and upgrade your Devicebook Smart Home.