Unfortunately, conventional floor plans are rather not suitable for us.
Yes and no. A single-family house for five children would be a property far from the market and would also require an ideal plot as a city villa (in terms of the concept with 2.0 stories). Conversely, "conventional" hillside plot floor plans are quite usable for you, only they need to be thought of with a "family connection" to the granny flat.
And a household for 7 people over 3 levels is more stressful than over 2
Of course, those rooms that can be "on the edge" of family life should preferably be moved to a basement and/or attic floor. The utility room does belong to the household, but socially it is not as important to be close together as parents' and children's rooms.
If necessary, one may have to plan a bit unconventionally and, for example, spatially distribute "the bathroom," with a shower in the personal hygiene bathroom and a bathtub in the wellness bathroom (next to the roof terrace) or something like that. To a certain extent, there will be some inconvenience to endure, e.g., in the form of climbing stairs between the pantry and the kitchen.
It simply is not a bungalow plot.