First of all, I would like to say, that I am pretty happy with your current house disposition. And maybe little less happy with exterior, but in the days when it was designed, that kind of "brutal" concrete architecture, was so popular.
Although, I was pretty happy with current design, re-designing to make it to accept your wishes, was not so easy goal.
My intention was to make as little as possible changes, both in interior and exterior. Why?
Well, it is very common to say "we will demolish these walls and make beams and columns it is easy!", and yes, it is, until the earthquake comes. Demolishing the bearing walls and moving the stairs, etc...are the extremely dangerous operation, and I personally avoid them every time I can. Thin dividing walls are different story... The same logic is valid for "moving" the openings across the exterior walls, as every opening/ door/ window has its own small beam above, and opening the new holes always means weakening the building construction.
If your house were single floor house, this statement written above could be change somehow, but as your house is 3-level house, I would not go with any kind of intensely re-constructions.
About levels number, if you could choose to add some extra level, you will need elevator for shore, which would make some crowd more in your floor plan design, so I did my best to fit all into current height of building. Personally, I would not like to live in family house of 4 levels, I think it is too much.
Sleeping area is in the middle of house, so you can easily go one level up and down, for every day life purpose.
1. GROUND FLOOR// PIANO TERRA
Here, on the ground floor, you will notice so many entrances. Even 5 of them. So, you may ask so many of them? Let's start to explain one-by-one.
1. Main entrance, is just in the middle of house, like it was before.
2. Secondary main entrance, is on the opposite side of the house, entering from the back yard, they both enter into same hall.
3. Left entrance is for co-working area only
4. Right entrance is for connection living room/ outdoor
5. Storage room entrance, if you have some big or dirty stuff, you can easily enter the storage room form outside.
1A. GROUND FLOOR// DISPOSITION
Right part: - Living, dinning, cooking, storage room// direct connection with outdoor seating
Middle part: - Communications only, vertical and horizontal
Left part: - Co-working consisted of 2 areas, divided by moving sliding doors.
- Laundry room with dressing room in the first part with WC
* - WC in the laundry area is enabled to use by guests/ everyone in the ground floor/ outside.
1B. GROUND FLOOR// OVERALL
The main intention about ground floor, was to place all the public functions and services at one floor, where they can easily access by guests, co-workers, etc.... If you wish you may even add some extra door at the stairs beginning. However, for you best and closest friends relax area is waiting on the top of the house.
2. FIRST FLOOR// PIANO PRIMO
This is sleeping area, with 3+1 separate bedrooms, with 3 separate entrance. For reaching the sleeping area, you may use the internal stairs, OR use 2 external stairs. Every of 3 bedroom areas has its own entrance, although the two bedrooms on the right part are sharing same outdoor stairs, which is not issue at all. 3+1 means 3 family bedrooms and 1 guest room.
On the right part, 2 kids bedroom area are placed. They are both equipped with same fittings, like bathroom, walk-in closet, and main room.
Left part is prepared for master parents bedroom (this time without fireplace, sorry! but let kids enjoy the romantic nights!) and guest room. For the bathroom, you may choose between one big bathtub or two connected standing showers.
Also, you can have separate WC and bath, or to connect them, as you want.
3. SECOND FLOOR// PIANO CECONDO
The last floor is relaxing area. Left part is SPA/GYM with showers, and left part is fun, like TV/ Cinema room, with small kitchen, WC and extra room which I called music room. Who knows, maybe one day, very soon, your kids become famous musicians? You'll never know...
Basically it is pretty simple, left part is outdoor seating for co-workers, while on the other side, you have more relaxing area with portable/ moving barbeque grill *-(I think it better than masonry grills, you can move them around and maybe throw out one day)
and small swimming pool, well it is not "swimming" but rather jacuzzi pull.
4A. OUTDOOR// PLANTS
Your yard is not too wide for some big plant species, so I decided to just plant them all around by fence, with original species from Meditterian area and Middle Europe.