Just thought I'd share my 2 cents.
I was a high risk pregnancy 2 yrs ago while being a witness and the HLC was involved with me. My likely-hood of needing blood was high and my baby's was even higher as he was born 3 months too early. I would suggest keeping the HLC off your case.
Now my experience was that the HLC came talked with me, the social worker, and some nurses but never with a doctor. They gave us some advice as to how to avoid blood loss i.e delaying the clamping of the cord. Although the hospital staff were all aware that I was a witness they would ask me privetly with no one around if I was willing to accept a transfusion.
Another thing, every healthcare provider must keep your file confidential. If you tell the midwife that you do not want her to share your info with HLC she will have to honor that (I believe by law in most jurisdictions).
Also, it is not standard procedure to transfuse mothers during or after a normal delivery...even if it's a c-section.
Congrats on the pregnancy and I hope you have a wonderful birthing experience!