You invite people for a reason, so you want allow them to develop and share their input. Therefor ask them to provide input without interference of others
Aks them to focus on "Why" Not Just "What": Don't settle for surface-level answers. Ask them to explore their underlying motivations and assumptions.
Ask to document : relate feedback to observations and data points. Move beyond opinions and anecdotes. This is crucial for analysis and the evaluation later on.
Ask to prioritize & Organize: Order the feedback when you give multiple answers to a question
Let them embrace change: Their input is good as it is, during the discussion you will learn about the input of everybody involved and after the discussion people are free to change their mind (or not)