You can channel wendo spirits into lifeless bodies, reanimating them to aid you. When using the animate dead spell, you can control 6 HD worth of undead creatures per caster level rather than 4 HD. In addition, any zombies or juju zombies you create using animate dead, create undead, or similar spells possess maximum hit points.
At 5th level, a cruoromancer can control up to 5 Hit Dice worth of undead creatures per caster level instead of the normal 4 Hit Dice of undead when casting the animate dead spell. He also gains the following blood infusion ability.
Bold for my reference. I'm fairly certain these do not stack, but I thought I'd bring it here to make sure. Would a Wizard (Cruoromancer) 5 / Juju Oracle 1 be able to control 7HD (4HD standard +2 from Spirit Vessels, +1 from Blood Command) when casting Animate Dead?
No, they don't stack. They don't add +1 or +2 HD to the base 4HD, they set it to a fixed value. Only the highest applies.
Hmm...I would say that Spirit Vessels ability would only modify Animate Dead when cast as an Oracle, and Blood Command would only modify Animate Dead when cast as a Wizard...
....but I would likely run afoul of this FAQ.
So, yeah, I agree with dragonhunterq, they don't add bonuses, just replace the normal value. No stacking.
Thanks for the confirmation!