Housing!

Hey everyone, my partner and I need some guidance.

I have two sons from a previous relationship one is 12 the other is 9, both the boys live with me full time (their mother left)

Now both the boys share a room and the youngest has ADHD, it has always been a struggle to keep him entertained because we live on a top floor flat with no garden. The youngest one wets himself which the older one gets annoyed about because the. The whole room stinks of wee. He has no where to go if things get heated with him, my partner recently moved in as we have found out she’s pregnant but we are worried things will only get worse with him because they’ll be a new baby so he needs to stay quite (which he can’t do) 

We need to move so we have more space and so he at least has his own bedroom, we don’t know what to do. Someone please help