are they broken from the binky?... if so, you may try whatever technique you used there..... but they have transition sippy cups with the round, rubbery nipple, but its not quite a bottle (i want to say nuby brand...?), you could try working from one of those to the soft sippy nipple to a regular sippy cup.... but honestly, with the 2 yr old, i would chop the top of the nipple off of his bottles and make them undesirable.... dip the nipples in lemon juice... something to make him not want it... and just deal with him wining.... but tell him things to make him want sippys too... "big boys use sippy cups"....(try not to be too negative though, like "botteles are for babies".... can have bad side effects like him throwing tantrums wanting to be a baby so he can keep the bottle... and self esteem issues because to a child, it may seem like youre telling him he's a baby because he uses a bottle instead of its intent that he needs to be a big boy and use a sippy)-- let him know what a good big brother he is and that he needs to teach sissy to use a sippy cup too so she can be a big girl...