Since I have no confident that the young pine is going to survive the potting (ref. to thread here) I have decided to try root cutting (?) on one of the young pine as worse case is it will die and loss of time/effort.
So, I cut away ~2/3 from root and coated with some root hormone at the tip and some to the hole before I insert it to the tiny hole.
I’ll just keep trying with lots of waiting.