Family Pack 2017 multi admins, how/possible?

Hello all,

Is it possible (and allowed) to install my 2017 Family pack on my brother's and sister's devices in their own home? I would like to let them manage the devices from their own login and not have them all appear (other than maybe a list) on my central account.

For example: 

My house (A) - 12 devices - managed with my account and login details 

Sister's House (B) - my subscription - her 6 devices - her account login details - she managers her devices

Brother's House (C) - my subscription - his 8 devices - his account login details - he manages his devices

Is this allowed/possible? Also, if it is, how many households can I install it in as I have my Parent's to do as well