Badly worded question. You lump in shamans with other classes.
I'm gonna have to say let's keep it classic. I am 100% sure all Shaman dots stacked, as I played a shaman in classic (but if you don't believe me, click below for proof.) They were unique in that respect IIRC. I don't remember the "blood line" stacking. Maybe it did. I just remember shamans didn't have "lines" of DoTs like other classes where the stronger one overwrote the weaker one; they had two "types:" poison and disease.
Whatever it was in classic, let's do it that way. All DoT a shaman had stacked with every other DoT that shaman could cast.
FOR SHAMANS, IT IS CLASSIC. CLICK FOR PROOF.
http://www.project1999.org/forums/sh...ad.php?t=54537