Will I be able to install games I bought digitally on my other Xbox?

Like the people in the other thread and like I said in my other thread - bought it digitally and it isnt showing on the xbox to install

That's incorrect, I never digitally bought the other games so why would they be aviliable for install?

What I did was set up the second Xbox, the one the other family members play on, as my 'Home' console. Everything I bought digitally, I bought and installed on that console first. I use the other Xbox One as my primary unit. As long as I'm connected online,
I have access to all the games I purchased and installed on the 'Home' console. You will have to reinstall them all on the non-home unit obviously. But after that, you can play with anyone else on the other console on any multiplayer game you own and have
installed on both. Hope this helps.

Recently bought disc game for my son’s xbox series x, however, some of the features of the game would not work properly so returned the disc & got a refund. Have since bought the same game digitally, but will not install as disc version still installed therefore asking for a disc. How do I override/rectify this ?

You'll have to delete the data from the disc version first which you should be able to to the same way youd delete any other game.

Once the data from the disc version is deleted off your system then it should let you start downloading the digital copy instead.

My other son's xbox is set as home.

This is because his xbox was bought first and is disc xbox.

The xbox for my son with the issue is series s digital xbox.

If we change the home setting to their series s digital. Will my other son still be able to play his games online on the older disc xbox?