Increasing density on second operation and using body hair

I plan to do 2 or 3 operations due to large area to cover and different donor areas. In addition to back of the head it's going to be the hair under the jaw and from stomach.

Let's say I do 30-35 grafts per cm² in first operation and want to increase it to 45 in second operation using body hair.

How should the first operation be done so the second operation is successful? Should the first operation have specific density or specific pattern of implantation?

And in general what is the best strategy when both the head and other donor areas are used? Should I do head to head only operation or can I do different donor areas in one operation?

Body is very tricks. Read this:
https://ishrs.org/2014/07/07/body-hair-transplant-2/

And choose the surgeon very wisely. I had a consultation with Mwamba on this topic and I would not recommend him for BHT (non beard)