Dr Mom
Thank you so much for your compassion and kindness for our loss of Kaylee.
There should be no problem in using Comfrey or BF&C. I used to put BF&C syrup into every bottle Kaylee drank, so, coming through the breast milk will be far more diluted than what she drank.
When I had an active midwife practice, I used to suggest that my mothers do 25 pelvic rocks every night before they went to sleep. This will help strengthen the ligaments and lower back.
After the birth, I used to put my mothers and their baby into a bath made from: comfrey, uva ursi and shepherds purse. I used a handful of each and then added 1/3 handful of cut golden seal, along with 2 or 3 cloves of chopped garlic and 1/3 handful of sea salt. You can put all of these ingredients into a cloth diaper or dish towel, fold the sides up and rubber band the top. Hold this in the running water, squeezing it as the tub fills up. Then allow it to float in the water as you soak. This bath does wonderful things to help the healing process begin. After the bath, my moms used a peri bottle with BF&C in it each time they use the bathroom.
I hope everything goes well for you and you have a beautiful birth experience!