Any ideas?

[labrax]

 My three year old son, Phoenix was potty trained at 19 momths and when he was 2yrs and 2 months he started peeing on himself because his younger brother, Alex pee-ed and pooped in a diaper so I guess he felt,' If Alex can pee in his diaper and get away with it why shouldn't i do the same". Lol. Cause at that time he tried to copy his younger brother a lot. 

My problem now is that Alex who is 21months, has completely reused to use the potty despite imitating Phoenix in all things. I put him on the potty to wee but he won't only for him to pee on himself the minute he's out of the potty. I really don't know whatelse to do cos it's frustrating for me especially as i'v got a 6 weeks old babay that demands my attention too.

And when he pees on himself, he sits tight and refuses to stand up so I won't know he's pee-ed but trust Phoenix to rat on him LOL... "mommy, Alex has wee-ed on himself" that's what i hear all the time.

I hear him crying now, Phoenix is announcing to the world that Alex has wee-ed on himself. I better go see the damage to my new sofa in the living room. (Sigh)

Any ideas on how to get a sturborn Alex use his potty,please? I'm all ears