It is possible to join several networks, in particular within the framework of a multi-site management: for example if you are in charge of the deployment of Mobility Work at the group level and you wish to be invited in all the networks of the group to follow its implementation.
If you already belong to a network, it is very simple to be invited in a new network: ask the network administrators (specifying which profile).
Once the invitation is made, you will receive a pop-up the next time you log in, offering you to accept or refuse the invitation.