Project with Multiple Assets - Stop accumulating costs on a specific asset

I have a scenario where I have multiple assets I am building. To simplify project / task setup, i am sharing costs across tasks for the multiple projects.

I have capitalized first 2 assets with the idea that the costs to date belong to the first 2 assets, then for subsequent capitalizations, I need to stop additional asset lines generating against the first 2 assets which I've already capitalized, how do I accomplish this?