The sleeves does not follow the hand movement

Hi, i tried making my first clothes cc conversion from adult to toddler. The result look fine, except that in game, the sleeves does not follow the hand movement, only the rest of the arm, which makes the mesh colide with the hand and it looks weird... I know my conversion isn't perfectand i am only looking for  way to fix the problem in the easiest way as i am still a beginer ! thank you :D
link to the dress : link