I just purchased AoE 4 from Steam. I have 3 boys that would also like to play. Is there a way we can all share the game without each person purchasing it separately?
Yes there is, but only one of you can play at a time. For multiplayer you would have to purchase separate copies or game passes. There is family sharing if your boys have their own Windows accounts and logins on a single computer. They would just need their own steam accounts if not already set up. Once their Steam accounts are set up, you can go to settings in your steam account and under the Family tab, check the 'Authorize Library Sharing on this computer". Then check each of their eligible accounts. You can do this under each of the steam profiles, that way they each get their achievements.
If you don’t want to do it that way, and I am assuming that with 4 you log in like the rest, they would each need their own Xbox gamer tags. Just log out and log in with their gamer tag. Be Aware that Windows will fuss because the log in does not match the MS Store account and if it is as temperamental as the other DEs, it would be a good idea before you launch the game to sign out and in with new gamer tag of both the Xbox app and the Xbox Console app in Windows.