HELP!

Alexis • 6:11:2016
Okay so when me and my SO first got together, his 3 year old was sleeping in the same bed as him. Obviously when I moved in, I wanted that to stop. For one, he needs to learn to sleep in his own bed and if we don't start training now this could be a never ending progress. 
He has these spaz moments where he can't go to sleep without daddy. So we lay him down, he'll pass out. Then around 3-5am he'll randomly wake up screaming for daddy and he'll get his way sleeping with us. 
But that's gotta stop. So we figured we were gonna make a chart for him and every night he sleeps the entire night in his own bed, he'll have a reward. 
HAS ANYONE DONE THIS BEFORE?! 
keep in mind, his mother said he sleeps in his own bed at her house all night. 
Why won't he do it for us?!