i have 3 invokes and yes they work independently. However some services like Spotify don't so you can only play music in one place at a time. This isn't a Cortana issue though, that's a Spotify issue. The way to get around this is create a Microsoft account for the devices and include the account in your Microsoft Family setup. The speakers can then share MS Family services (Family Calendar, Family OneNote, Skype) but are separate to your personal account. You have to have a Spotify account for that account too though. I have my home setup so my 'family' account is hooked up to the devices at home and my personal account on my laptop, phone etc. It's great because the family account then allows me to call my home when i'm out via skype and all the devices around the house will ring so anyone anywhere in the house can pickup. cool!