We suggest that you can add your contractor as a manager. You can use our shared user function by adding manager of your each device. Please note shared users must have a Netro account.
Manager can use all the features of the shared device except deleting controller, changing address, deleting or adding sensor. The shared person who have registered our app can be added to your account by his email and then he is also be able to see your device on his app. Please see this article about how to use the shared user. http://www.netrohome.com/forum/posts/147
Please let us know if you have further questions.