Awwww they are so precious! Okay back to the question haha. Maybe you can try olive oil (for hair, not the cooking kind)? I heard it's pretty good with stimulating baby's hair. When I was a baby, I didn't have a single strand of hair on my head at all till I was about 2.5 years. My grandma used this old school Indian hair oil from a company called M.B.R and apparently that did the trick.
Cute little ones! Don't worry, my children had little hair when they were born n I put some baby oil each time after their bath n now, my toddlers have abundance of hair. They will grow more hair As they grow. Ur babies are considered having more hair than mine.
The hair growth rate differs for every baby. I have a couple of friends whose babies took up to two years to get a full head of hair. Slowly but surely. And.. can I just say that your babies are so adorable! :)
Hair growth are inherited. Don't worry, they will grow, you can try to apply a thin layer of olive oil before bath to encourage the hair growth.
The faster way is keep shaving and shaving.
BoonCheong Poh