Using family members Apple TV4K as HomeKit Hub.

Hi,

In my household we are 3 family members, my son, my daugther and me.. In our setup we have a lot of HomeKit devices, and 4 pcs of Apple TV4/4K´s in total .. 2 of these are using my Apple ID for iCloud, and my daugther and son both have their own Apple TV4/4K logged in with their own Apple ID to iCloud .. Both my Daugther and Son are members of our Family Sharing, and both are members of HomeKit group, with me as owner.

Now my question is, why am I not able to use my childrens Apple TV4/4K´s as a HomeKit Hub, and having their Aplle TV´s showing up in the Home app like my 2 Apple TV´s are doing, when they are part of my family!?

Regards

Stig :-)