When you create(invite) user, you see QB window to select QB Customer (after you tap on button “Invite”).
In the User Management table you see which client is connected to QB Customer, which is not. You have ability to connect certain client to QB Customer from the table, also “Reconnect”(if connected already) or “Disconnect” (If connected already), show loader (corresponds to row with customer that is about to be connected?).
3. On “Invite/Edit User” you can either “Connect” (If NOT connected already) / “Reconnect” (If connected already) / “Disconnect” (If connected already) the user. On this screen you can see which QB Customer is connected to this client.
NOTE
we can have custom design, but also plugin to connect QB provide custom connector block: