Hello.
Solution for your family apartment is next.Regarding living room,ti stay without any changes about space,I placed there a lot of bookcases for your books,and
one of them separates living room from dining and kitchen.Wall in living room next to the dining space was moved out,and now makes unique fluid space( living + dining + kitchen).
One room I make for two children older,with two beds and desks.And baby get room near parents,with sliding door which is conected with master room.
Bathroom I didn`t changed,exept bathroom near studio,where I expand a little the wall where was tube,and now on that place I put toalet.
I make separate room just for studio,with one sofa,bookcases, desk, and armchair.
Entry space is fluid too,some walls is removed(off course if that walls is not structure walls) to avoid too much corridors.
Your furniture is keeped,wooden comode is in dining room,heat is in kitchen,lamp is in studio corner.