4 yr old male staff marking everything

hi everyone

i am desperate for some advice, my 4 year old staffy keeps marking eveything. It makes no difference if its indoors or out. I will give you a bit of background info just incase there might be some clues in there! I've had him since he was 10 wks old and i was still living at my mums house (im only 22) he went through the normal puppy stuff and then as he got older he stopped doing stuff like that in the house other than when he got excited he used to wee! Anyway i fell pregnant with my son and my partner had moved in with us with his young pup, which is also male. We moved out and got our own place and then my dog just turnt into this nightmare animal!! We thought he would settle down and maybe it was just the new home and the fact that we had a baby and another dog for him to live with but its been over 2 years now and he is not getting any better! i've since had another baby so have a 2yr old and a 7mth old aswell as these dogs which are 4 and almost 3. Im at my wits end, he goes into my sons room and wee's up his bean bag (he has done this 3/4 times) and has just this morning gone in and done it up the corner of his bed and all over the cover... i cant keep up with him. Im so close to finding him a new home but i really dont want to have to do it.. it will break my heart! But would it be the best thing for him? the other dog doesn't and NEVER has done this so surely its not a male dominance thing coz he is the only one that does it! He knows its not acceptable because if i catch him doin it he legs it to his bed and lays down. what can i do? please help.
thanks
charlie

No it`s not dominance - but it is a male thing. (Territorial marking - quite normal.)
I`d neuter the dog and clean everywhere with a non-ammonia based cleaner to stop him going back to them.
To break the habit you could keep him close in the house?
When out, jolly him along when he stops to sniff. He can do his sniffing and marking when off lead.