@rvds61 

Hello, you can connect them like modem---main Deco )))((( satellite Deco A )))((( satellite Deco B; considering the third Deco won't work as long as it is 10 meters away from the kitchen, we can do some troubleshooting first. 

1. Can you detect the wifi signal from the second Deco when you are in the room? What about the signal strength?

2. With the third Deco located in the room, what is the led status of it? And which Deco it has connected to?

Note: You can find it on the Deco app. 

3. Try to reboot the whole Deco system and verify whether the third Deco will connect to the second unit. 

May it help.