I have two servo skulls right now, one medicae, utility with a combi-tool. Assuming I succeed in ordering them to help me (or they have prior standing orders to do so) can I use those servoskulls to give me a +10% assist bonus for their respective tasks?

So far I've been playing it as yes, I can order the servitors to assist me, granting the bonus. However, I wanted to make sure I'm not screwing anything up and making things too easy.

After all, failing some tests can make a game more entertaining.

I'd assume that most skull owners use them as assistants. IIRC, a Medicae skull has a 20% or 30% chance of making the roll on his own...