Dear Client,
I tried to intervene with the space as low as possible. so, i proposed 2 design options. I also showed how to achieve the construction. The childbed room is blind, as it is only for sleeping. But, i included study table for the childrens. I created a common space in front of the toilet, with internal doors from the rooms to maintain privacy of each room. I suggest that, option 2 will be better for you, according to my proposal.