I had to think about this great series, but in Germany there were only the first 2 seasons shown. So, I’ve checked some episodes of the later seasons.
I found rather few bedroom scenes. The oldest brother Thomas still has a room for his own (dark blue walls with a Che Guevara poster, unpictured).
Pic 1 is from s3e12 showing the same messy room of Oli, now ~13 yo (left) and Zac ~10 yo like in the earlier seasons.
Pic 2 from s4e20 showing 11 yo Zac, maybe in the same blue room. I think, I only have seen one bed. Maybe Oli now has a room for his own or Zac is in Oli’s room? Or Oli sharing a room with Thomas?
Pic 3 is from s5e5 again showing Zac but in a light grey and yellow room with one bed only.
Main entry rating 5 (series much better, but Oli looks much older in later seasons)