issues with 3yrold,, sorry long

[mushpea]

I have had a 3yr 3monthold since she was 11 months she has 2 older sisters 1 of whom started school this year,, before she started school the middle one used to tell this child what to do constantly no matter how much i told her not to,, 'come and play this, hold my hand, not like that like this' to the point that when the middle child was at nurseyr the younger one was totaly lost and didnt know what to do or how to play,,, i did try explaining to mum but she didnt see a problem,, now middle one is at school and 3yrold is having issues,,, she screams when she arrives in the morning as she wants to be with her sister (who I have after school), she settles really quickly but through the day she dosent know how to play on her own,, some days i have a 2yrold and almsot 3yrold and she will quite happily boss them around and tell them what to do!! I do stop her and explain why but then she just sulks,,, today i will only have her and a 10 month old and she will constantly be glued to my side yapping about her sisters,,, she wont go and play on her own not that she should iall the time,, i do play with her but I do think its good for them to learn to play independantly too,, if i play with the 10 month old she muscles in , if i say i will play with you in a minute she sits there staring and waiting,,, if we go to a toddler group she will find a pram and just stand with it the whole session and if we meet up with other minders to play she will not want to leave my lap and when i get up to do somthing she isnt happy to play.
how can i get her to A. play on her own and B.engage with others without being bossy