Floor plan design - Two-family house / Single-family house with a granny flat

Hello everyone! Basically, it is about a two-family house, but the second residential unit should be on the ground floor with about 75 sqm.

Development plan/restrictions
Plot size: Outer area with 45m*45m (2025 sqm)
Slope: No
Floor area ratio: -
Gross floor area ratio: -
Building window, building line and boundary: -
Edge development: none
Number of parking spaces: -
Number of floors: -
Roof shape: -
Style: -
Orientation: House is freely rotatable, currently the entrances face north/northwest
Maximum heights/limits: -

(little restrictions due to outer area)

Requirements of the builders
Style, roof shape, building type: Rectangular floor plan with simple gable roof and waiving of gable/dormer etc. for economic reasons, style plain country house, KFW 55
Basement, floors: No basement for economic reasons, 1.5 floors
Number of people, age: 4 (30, 30, 60, 60 + max 2 children)
Room requirements on ground floor, upper floor: Ground floor secondary apartment completely on one level with ~75 sqm living space; other residential unit ground floor + upper floor at least 150 sqm living space, somewhat more desirable
Office: Home office for 2 persons
Overnight guests per year: none
Open or closed architecture: Tendency to open
Conservative or modern construction: Tendency to conservative, country house style
Open kitchen, cooking island: Open kitchen, cooking island optional but not mandatory
Number of dining seats: 6
Fireplace: Would be very desirable, chimney usable for both parties if possible (therefore living rooms adjacent). However, not built-in but initially only the chimney, to which a freestanding wood stove can then be retrofitted.
Music/stereo wall: -
Balcony, roof terrace: Roof terrace quite an option, since there is little space on the ground floor (just under 62 sqm) and a lot upstairs (just under 113 sqm). The idea would be: enlarge the floor plan (e.g. by 2m) and then create a roof terrace on top.
Garage, carport: Waiver for economic reasons
Utility garden, greenhouse: -

In the attached plan the current idea is to remove the pantry and simply add it to the kitchen, also give about 1 sqm from the bathroom to the kitchen. This will shift the kitchen a bit further to the back and it will no longer protrude so much into the living/dining area (and then there will be an additional door from the hallway to the kitchen). However, we still find the almost 62 sqm downstairs somewhat small, so we are considering at least 10.99 x 17.11 in favor of our WE1. But that makes the problem worse that we get even bigger upstairs (we already think it is too big now). Therefore also the consideration of the roof terrace.

What we like:
Dining/living area + kitchen in an open L-shape.
Shower in the ground floor bathroom (outdoor area: you often enter the house dirty)
Small storage room for beverage crates and similar
Extra "corner" as a wardrobe area where you can immediately get rid of dirty stuff.
Deliberately two separate entrances (so it is not really a classic secondary apartment), absolutely must be like this.

We are not yet satisfied with the upper floor. The utility/technical room must be upstairs. Also a second larger storage room. Also a spacious, walk-in dressing room is mandatory. However, it should be one double office, no two rooms. Office 1/2 could then become a "hobby room."

House design
Who created the plan: Preliminary draft by architect
Preferred heating technology: Air-to-water heat pump (LWW)

If you have to do without, on which details/extensions
-cannot be done without: Secondary apartment (WE2) 75 sqm on one level. Shower in the ground floor bathroom. "Wardrobe corner." Two separate entrances.
Otherwise we are still quite open, especially regarding the allocation upstairs.

Why did the design turn out the way it is now? For example
Preliminary draft architect after discussion

What is the most important/fundamental question about the floor plan summarized in 130 characters?

The fundamental questions are:

1) If we enlarge the ground floor and plan part of the upper floor as a (simple) roof terrace, is that economically sensible? Or is it cheaper to simply convert? That is: Does the saving upstairs through the roof terrace compensate the additional sqm downstairs?
2) How would you solve the problem that downstairs in WE1 there is rather too little space and upstairs rather too much? WE2 must necessarily be on one level at about 75 sqm and a basement is not an option. The floor plan should also remain as rectangular as possible for economic reasons.
3) A glass extension to create space on the ground floor would also be conceivable. But expanding the floor plan is probably more economical than creating 15 sqm by a glass extension e.g. in the dining area, right? The glass extension should be fully insulated if anything, that will really cost.
4) How do you estimate the construction costs? :)

Additional: The design of WE2 can be accepted as is for now.

Thank you very much in advance...

Outdoor area

And why are you allowed to build there, and under what conditions?

However, the house is freely rotatable, currently the entrances face north / northwest

Do you mean mirrorable?

And why are you allowed to build there, and under what conditions? Do you mean mirroring?

It would be a replacement new building including a senior citizen share. Conditions would be a maximum distance of 200m to the old main building. Normally, it is also a maximum of 250sqm living space, but since the old main building is being repurposed (=condition), areas can be credited so that we should exceed 300sqm living space. By mirroring I mean that on the one hand the sides can be swapped and on the other hand the house can be rotated arbitrarily in terms of orientation. Approval has not yet been initiated, but according to the architect, we are not subject to any further restrictions (is there anyone with experience in the outdoor area here in the vicinity - by the way, it is in NRW).

Are there still any missing information perhaps? Or is the floor plan in its design complete nonsense? Suggestions for improvement of any kind are welcome, including criticism.

Well, it's always hard to understand something like this.

- Bathrooms ground floor ... why windows in the showers?
- Bathroom upper floor - the shower is half in the ceiling area 150 to 200 cm ==> unsuitable

You always write this and that also for cost reasons ... where is the budget? Perhaps one can save words about [Dachterrasse] etc. ;).

And the plot and location to the street, neighbors, etc. I always find VERY important for the assessment of a floor plan

At first glance, the rooms seem very carelessly put together.

In the granny flat:
The living room would be too small for me. Is an open-plan living kitchen not an option?
Does it really have to be such a small dressing room? What is the advantage compared to the old-school version of a wardrobe in the bedroom?

Is it desired that the two terraces are right next to each other?
Possibly in the granny flat facing east?

Upper floor:
Here too, the dressing room would be too small for me.
If you only need 1 office + 2 children's rooms, I would plan that way and make all the rooms a bit larger.