Absolutley, otherwise where would we fit the litereary convention of only finding out about the kinship after you have slain him (cf Balin & Balan for a start).
"Someone in the clan" is, of course another option. According to the Lawspeaker it's not Kinstrife, because the Gagarthi is outlawed. According to the Chieftan it's not Kinstfife, because Humakt is severed and so "not kin" - but if the Outlaw's sister (or mother, or cousin or another brother etc etc) still regarded them as "family" and so is turned against the Humakti for carrying out the act and/or the Clan for sanctioning it then the seeds of disaster are sown and the evils and jealousies of the pre-dark can find their way in to the heart of the clan...
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