Find my friends - one account multiple iOS devices

In our household we have one Apple ID / account. We do have multiple iPhones on which the Find my Friends app is installed.

So far i do not succeed in using this app to follow our own devices. Do I need to have separate Apple accounts for these devices in order to use this app?

If eg. I invite my wife she does not receive the email or request on her iPhone.

Appreciate your insights here.

Thanks,

Dan