Can a space have a related federation?

Yes! Though spaces and federations are different structures, they need not be mutually exclusive. While some individuals only want to run federations and some only want to manage spaces, there will inevitably be those who want to do both. 

In this case, guardians can create a companion space to their federation and add the space invitation code to their federation's meta fields. This ensures that anyone who joins their federation and receives a wallet also automatically joins the related space.

This way if members of the space need to pay one another, they can do so simply via chat by sending eCash from their associated federation wallets – keeping their transactions private, fast, and inexpensive.