Chico, on situations as you're describing, unofficial visits when coach has been in contact, I've found with my older son (2017) that coaches absolutely wanted parents along. Twice I was going to wait, just like you, but the coach wanted told me to tag along as well. At the point you're at, they want to see what the parents are like as much as the kid. I think it gives them a better read on the character of the prospect. From what I experienced, they will read you as much as they read him. Others will have different takes I'm sure and not all coaches are the same. This was our experience. Let him do the talking and guide the visit, but (on unofficial visits) coaches wanted to meet parents as well.
Official visits or when visiting on the invitation of the coach, it was different. At that point, the coaches had the information they wanted and were only interested in the kid. At that point, we stayed in the lobby. But I think you'll find on most unofficial visits, the ones you initiate, the coaches will want to meet the whole family. In fact, several coaches wanted to meet sons younger brothers as well. Good luck!