Possibility of automate link subitems from another board

Dear Support,
I have a problem with the mirror subitems from another board.
I would like to choose the client (red arrow) and next choose the machine (violet arrow). After this solution I would like get unique serial number from board Customer list (yellow arrow).
Have you any idea how I can do it?

At this moment I did it manually
First board

Second board

Hi Piotr,

Thank you for your explanation :pray:

In order to mirror that subitem data (specifically the machine type), you’d need to set up an additional 2-way connect board column in the subitems on your customer list and connect it to the item in Service and Maintenance board. I am afraid it isn’t possible to mirror subitem data through the parent item via a connect board column. This way, once that subitem connection is set up, you can mirror the serial number from your customer board.

Does this make sense?