Family Wagon
You can only have one adviser that is not a 
. You can have any number of advisers- they ignore your adviser limit.
Q: How does this interact with Pied Piper?
A: You can always play Pied Piper after Family Wagon. If you play Family Wagon after Pied Piper, you can only keep one non-Nomad adviser, so you could keep Pied Piper or one other non-Nomad card. (This ruling has changed.)
Q: What happens if I play this into my advisers and already have three Nomad advisers?
A: Nothing, this is okay. You check whether to discard based on the new adviser limit prompted by the card you are playing. In this case, Family Wagon will increase your adviser limit and allow you to play without discarding. (This ruling has changed.)