Thansk for the follow-up question Perttu Talasniemi. As I briefly mentioned in my last reply, I find it beneficial when designers work closely with architects, programmers, and testers as part of a cross-functional team. This team should own the solution including the UX/UI design.

You are right: Aliging the stakeholders — people from marketing, sales, support, and other departments — is crucial. I discuss stakeholder managemennt in detail in my book How to Lead in Product Management. But you my find the following two articles a helpful starting point: Stakeholder Management Tips for Product People and Getting Stakeholder Engagement Right.

Hope this helps!