Tu partages ta chambre avec ton frère. And in the 1st. person it is: Je partage ma chambre avec mon frère.
There is no law about that.
It is not illegal for siblings to share a room. Age has nothing to do with it.
I would say never
a bedroom is 'une chambre' (fem.) in French.
a bedroom is 'une chambre' in French.
'the bedroom is ..' translates as "la chambre est ..." in French.
a master bedroom
It's legal if they're brother and sister, maybe.
My bedroom is 'ma chambre' in French. This is a feminine noun, even when it's a boy's bedroom.
bedroom of the parents
it is not illegal for a brother and sister who are aged 5 and 2 to have to share a room in New Hampshire. The parents can however have them in different rooms if the space permits.
i think it's better to have your own bedroom than to share one , but it would be better to have a big bedrrom !