If Imarë wants her own dog, she should perhaps just come out and say so. Personally, I suspect she pines for the last hound with which she enjoyed some intimacy, as I believe the fate of his various parts was adumbrated amongst her other to-do list bullets.
I must say, with all due diffidence, that I hadn't considered the Aleathian Odyssey in trying to unpuzzle my family secrets (who authorized this guy to have Harnplayer?
). Having said that, I wonder whether the connection you are hypothesizing is a little too removed to account for my mistaking Koltho for my brother. At the same time, I have been thinking along similar lines in one respect: perhaps Sir Peten inherited his Deryni blood from his mother, while the red-haired trait came from a non-Deryni father. We do not, for instance, know to what degree Peten was a full-blood Deryni.