Value Stream Map- Two independent Process combining giving Next Process

We tend to overcomplicate. I’d look at the main process by itself and treat the contributing processes simply as steps. If one is causing an NVA situation, that will become clear. And then you can look at that by itself to better understand why, and how to improve it. If you’re familiar with Theory of Constraints, I’d look at the VSM in those terms. ToC identifies the bottleneck that constrains the process. That is, the process cannot be faster or more productive than allowed by that constraint and, according to ToC, anything else you try to improve is either ineffectual or causes more waste, such as accumulation of WIP inventory. You may find that one of the contributing processes is the constraint. Then and only then should you look at the details of what’s happening there.