Okay. I've recently developed a bit of a "theory" regarding Teir's mother, especially the whole If Kahvi is his mother, and left when he was just a tiny baby, how can he remember his mother leaving with his younger brother?
Here's what I think might have happened:
During Kahvi's travels she met Teir's father and recognized him! Not exactly being too fond of the concept of recognition, and perhaps thus not wanting to raise a child born from it, she stayed only long enough for her child (Teir) to be born before she left. I seem to recall somewhere that he was 'raised by wolves', as in was breastfeed by them, maybe his father used his "Animal Communication Skills" to get some stand-in nursemaids for his son...
Then, some years later, Teir's father met another woman and they fell in love. This is the woman Teir refers to when he's talking about "his mother". Together the two had a child, Teir's (half-)brother, born without recognition!
Would also explain why Teir's father said it was easier when Heart Meets Heart.