You can avoid losing Pet Pal.
1) Simply refuse when she offers to teach you more source. If you already have 3 source points, you don't need any for Hanag and this also saves 3 bears lives. Hanag will still give you a source skill book.
By robbing and then killing her i got like 7-8 source skill books... maybe it was inhumane but quite useful ;>
Anyway thanks, i will try your advices when i will play for the 4th time. Maybe even very soon, because i feel like there's still a lot to discover and test various builds, even if i've finished the game 3 times. (twice before DE, once with DE).
