User inbox replies

Greetings. I have 2 users in PlaySMS (user1 and user2). How can I have it so that when someone responds back to user1, the response will only be sent to user1 inbox. When someone responds back to user2, the response is sent only to user2 inbox?

Right now, all responses are sent to “sandbox”.

Settings - Route incoming SMS - Post Rules - Route all sandbox SMS to users: gives me the option to add user1 and user2 but responses are sent to both users. I don’t want messages sent to both users. I only want messages to be sent back to the original user.

Is this possible?