Table talk (Bibracte)

Not sure if this has been addressed yet or not (and if so, I apologize, as I seem to have either missed it or forgotten), but are there any rules for bringing one's companion/grog into a magus's thread uninvited?

Reason I ask is that I can verily easily see Wilhelm the Forester showing up in Onesiphorus's thread, seeing as how he doesn't spend much time in the covenant itself, but spends most of his time in the surrounding woodlands. Yea/nea/give me a moment?