When I sign onto my XBox Series X, my wife or son get kicked out of their game on our XBox...

Hi, Hawkman332! thank you for reaching out.

My name is AJ, I'm an Independent Advisor for the Xbox Community.

I'm sorry to hear your family is experiencing some issues with your consoles.

Is the Xbox Series X designated as your "Home Xbox"? you can see this by signing in to your account and going to Settings > General > Personalization > My Home Xbox.

I'll be looking forward to your reply.

Best regards.

Hello Simon, it seems that what's happening is that you are switching accounts locally on the console but you remain signed in onto your Wife's Xbox account, when this happens, you get kicked if your wife signs in onto another console because she is still
signed in onto the other console which I assume is the one where you play, I suggest you to set up the Home Xbox while being signed in on your wife's account on the console that you play and then just make sure that you're signing in to Xbox with your account,
in that way, your wife will shared his subscription benefits as well as games. I hope this explanation works for you. Let us know if you have more questions.

Not really...

Xbox Series X games / upgrades / updates has to be installed onto the Series X internal or expansion card SSD,

You can have Xbox One games on your external hard drive that will get an Series X upgrade but the games will need to be transferred to the Series X and then the Series X upgrade will need to be downloaded onto the Series X SSD,

As an example...

I have Marvel Avengers on my external hard drive that will get the Series X upgrade and I will transfer the game over to the Series X SSD ready to download and update the game to the Series X version when available.

Okay so just to make sure I understand.....

I make my sons Series S (MY) Home Console.....

He can play Online with me if I am on my PC signed in as me.
I can also sign into my own Series X and play my games.

We wont be playing together on XBOX on both Series S and Series X.

Elaborating slightly: None of our family accounts on the same xbox aside from mine have xbox live gold (ultimate in my case). Previously on xbox one x, for instance, my wifes xbox account, she would sign into MWF3 360, go to live and join games. Now on
xbox series X, same exact steps, it throws the error. You could always play under other accounts as long as one account was a live paid account (360 or regular xbox one x titles), now it only works for one x or one x series x titles.