Hi arty angel,
how old are your another 2 girls? is it because that both of you are spending more time with the other 2 that causes her to be jelous so trying to get more attention from both of you?
one way is, while you are attending the other 2, your hubby will play with the 3 years old and vice versa.
secondly, set up a house rule, post it somewhere where all can see. keep it short and simple and not too much restriction. you can discuss with hubby about the rules.
thirdly, set up a reward chart for all 3 girls. each will be rewarded a sticker (let them choose) if they follow the house rules set. set an achievieable goal for them, ie, if they have 10 stickers, they can go shopping,.. have their favourite snacks,...etc,..
lastly, set up a naughty corner whereby is visible and not dangerous. if they break the rules, tell them but not shouting, give 3 warnings before sending them to naughty corner. they may cry or walk out, put them back and dont talk to them (but check check and make sure they are ok). the timing to stay there depend on their age. after times up, you go to them, ask them why u put them there. explain to them for better understanding. ask them to apologise and give a hug, telling them that you still love them.
its very changelling for parents nowsaday to bring up their kids. try to be patience, if you loose your cool, its better to have a time-out yourself ok. kids grow up very fast. bond with them while they are still young and cute.
take care and good luck.