Generate & maintain dropdown list from items on another board

We have an application where I’d like to have one board as a “Customer List” where each item is a firm. I also have a “Projects” board where I would like to have a dropdown column with options that are made up of items on the “Customer List” board.

And when new customers are added, or when a firm’s name changes, we can update it on the “Customer List” board and it will propagate to the “Projects” board dropdown column.

Not sure how best to handle the situation when a dropdown selection that exists for an item on the projects board is no longer on the customer list. Might require some special consideration or at least clearly showing what will happen. Not sure if it’s best to just force that change to propagate from customer list board to dropdown column in projects board so all “old” instances of a customer name all get updated to the “new” name that gets updated on the customer list board. I can see times where different companies might want flexibility on how that is handled.