<human>: Can you condense the text into a few key points?

We've been dating for 9 months now and it's pretty serious. She(24yr) has a 6 yrs old son. I(31yr) dont have any kids and have never dated anyone who does before. The father isnt in the picture at all and pretty much never has been. I feel like I am at a crossroads when it comes to the raising of her son. He spends a ton of time at his grandmothers. The problem is they coddle and baby him way too much. 

Anytime he meets failure or adversity he immediately quits whatever it is and most of the time starts crying. In turn they immediately do whatever it is for him so that he is happy. This is something as simple as trying to put on any items of clothing, playing with his toys and he cant figure something out, or he cant open a simple candy wrapper. Most of the time he doesnt even try, he just says I can't and they do it for him. He can't sleep in his own bed and when he is over my house and he can't sleep in the bed with us(I wont allow it) it causes huge problems. At his grandmothers he sleeps with her all the time. When he doesnt get his way he cries until he does. Early on I noticed that his crying stops instantly the moment he gets what he wants so I told his mom it's his mechanism to get what he wants from them. He tries it with me and I tell him I won't have any conversation with him until he stops crying/whining first. His grandmother doesnt like the way I am with him because she said I am not nice enough to him and I treat him like he isnt a kid. I've never yelled or said anything mean to him. I just won't tolerate the crying/whining/tantrums so I tell him to calm down and speak normal, he just ignores me and runs to his mom/grandma. I feel like the path they have him on will lead to bigger problems down the line. Any advice on approach? Grandma discounts everything I say because "you dont have any kids".
<bot>: Dating single mom, grandma and mom baby/coddle kid too much. My input is discounted because I dont have a kid myself.