Desing-responsible

I read your question and I remember ISO 9001:2015 clause 8.3.2 d). 

Let us look into design and development as a process:

Who is going to collect the design and development (D&D) inputs?
Who is going to perform each activity in the D&D project? For example, who is going to develop a new specification for the landing page? Who is going to test it? 
Who is going to have authority to make decisions during D&D revisions?
Who is going to have authority to make decisions during D&D verification?
Who is going to have authority to make decisions during D&D validation?
 
A quality management system has to plan authorities and responsibilities for those important activities.
 
The following material will provide you more information about design and development:
 
-      The ISO 9001 Design Process Explained - https://advisera.com/9001academy/blog/2013/11/05/iso-9001-design-process-explained/
-      Procedure for Design and Development - https://advisera.com/9001academy/documentation/procedure-design-development/
-      Free online training ISO 9001:2015 Foundations Course - https://advisera.com/training/iso-9001-foundations-course/
-      Book – (where I use the process approach this way) - Discover ISO 9001:2015 Through Practical Examples - https://advisera.com/books/discover-iso-9001-2015-through-practical-examples/