I tried to follow all your needs creating a new master bedroom in an extention of your house
The idea is to have a dressing room that is in between the bed and the terrace in a way to allow you to use it as a sort of veranda!! so you can enjoy both in summer and winter the sun there! taking a coffe with the window open or enjoyng the sun while dressing in winter ! is a sort of relaxing space sourrounded by the wardrobe boxes. In the suite there is also a big bathroom. I chose to take a part of your bathroom to give a second one for people using the first floor instead of going in your room. THis second bathroom is very essential but useful also for your friends.
The kitchen and the livingroom are a one big space with a squared fire place in the middle that divides the spaces : you can sit around it and enjoy the warm while eating or reading or relaxing on the sofa watching tv.
The ground floor is divided in 4 different rooms: the relax room or atelier , the laundry, the cellar and another room for hosting people.
The second floor is all for your kids everyone has a room and they have two bathroom to share.
With this proposal you can have :
5 bathrooms
5 bedrooms
and two livingrooms and relaxing spaces
In order to get as much light as you can i left the first floor as an open space