Multi-Flat Residential Design Project

I'm looking for an experienced architect to design a residential building. The main task involves the division of the land into three separate flats. I would also appreciate if you could provide some ideas on the best way to include the following:
- Specific features for the flats (Balcony, Ensuite bathroom, Walk-in closet)
- The number of bedrooms in each flat
- Any additional amenities and facilities that would be suitable for common areas.