Lovro, I do mine very much like Stephane mentioned. Do each one as an individual listing, but you can also, on only one of them, list that it can sleep up to (lets say 8 beds, so sleep up to 16) guests. But put in that they have to contact you prior if they need more than (the amount of beds you have in one apartment).
Example, I have an 11 bedroom house, I list all bedrooms individually, sleep 2, but in one listing I put that it can sleep up to 25, (however airbnb only goes up to 16). So I put that one in airbnb as 16 guests, all other bedrooms as 2. But I put in the description that if they have more than 2 guests, contact me before booking to see if the other rooms are available. So I get a lot of big groups, which is financially great, as I add $38 for each additional guest, and they book the whole house when available, or I tell them one of the rooms is already booked, so they can only have... # of bedrooms. Just a thought.. Keith in USA