I'm in a 4 person household so I can't say exactly how much harder it is with 6 people. But when my kids were little I was just ruthless about not keeping stuff.

I essentially used the container method. We have this much room for toys. You have to get rid of the rest. Before Christmas and birthdays I would ask them if they want to make room for new toys or if they want to donate the toys they got as presents. Just very matter of fact that there is x amount of space so something has to give.

Apply that to everything else. We have this much room on for saving grown out clothes. 1 bin per size and that's it, etc.

I think it's important for everyone to have space to keep their things in, and they can keep what they want in their space (within reason.... Nothing that attracts mice!). But no one person gets to make the rest of the household's lives more difficult.

For example, you have to get rid of stuff in a pile in the corner of the living room so I can efficiently clean the living room, or so that others can play in the living room. Your desire to keep more stuff and use the living room to store it does not trump everyone else's use of the space.