I agree, if u dont praise them for the good things they do, they will go and do bad things for attention! Whether good attention or bad, they need it!
I dont agree with what someone said before about having fun with harley whilst she is in naughty corner coz then she will just get more jealous of her lil bro and it will ruin their relationship! Get her involved in his daily routine..feeding..changing etc and give her the role of 'big sister' rather than, 'ive replaced u with a good well behaved baby'!
I think the naughty step/corner/chair works well if its done right! Just make sure u praise her for being good more than bad and she will get the hint!! Jaycees always trying to help me!! When i get her chair out she's all, 'ill help mummy!!' lol bless!