How do I manage objects in pairs

I have two objects that I wanna ally in pairs.

I have a Door and a valve.

Both have an ID value, and the valve has an activation rate.

I want the door to open partly using the activation rate.

However, I cannot see how to do this. How to retrieve the correct activation rate value in the door's width expression depending on the IDs.

Because the thing gets glitchy when I have more than one door and one valve.

https://www.scirra.com/manual/150/containers

Thanks, that might do the trick. I knew how containers worked, however, I never thought of it that way .

I'll try and let you know.