Declare that this Tor relay is controlled or administered by a group or
organization identical or similar to that of the other relays, defined by
their (possibly $-prefixed) identity fingerprints.
This option can be repeated many times, for
convenience in defining large families: all fingerprints in all MyFamily
lines are merged into one list.
When two relays both declare that they are in the
same 'family', Tor clients will not use them in the same circuit. (Each
relay only needs to list the other servers in its family; it doesn’t need to
list itself, but it won’t hurt if it does.) Do not list any bridge relay as it would
compromise its concealment.
When listing a node, it’s better to list it by fingerprint than by
nickname: fingerprints are more reliable.
If you run more than one relay, the MyFamily option on each relay must list all other relays, as described above.
Note: do not use MyFamily when configuring your Tor instance as a
brigde."
HTH,
--Torix