How old are the children?
First of all, do not allow them to nap during the day or fall asleep in the evening in the parents' beds. Let them know that Mommy and Daddy have their bed and that the kids have their own beds.
If they are young, give them a teddy bear or favorite blanket to comfort them.
Make sure that they have a consistent bedtime with a routine such as reading a bedtime story.
To get them to stay in their own bed at night, a parent may have to start by sleeping on the floor next to them until they fall asleep if they are not willing to stay in their bed.
I f they can start off by staying in their own beds, then check on them every 5, 10 , 15, 20 , 30 , 40 minutes etc. until they fall asleep.
If you start out by putting them in their own bed and then they wake up and come in your bed, take them and place them back in their own beds. Do this no matter how many times is necessary but you must not talk to them during this process.
Your children need to be trained with much patience and dedication on your part for this process to work. It will not happen over night. Amidst the tears, screaming, and even throwing up regards XXXXX XXXXX wanting to stay in their beds, your children must learn to stay in their own beds. You may even want to place glow in the dark stars on their ceiling.
If you need further assistance, please let me know. I hope that this has helped. If so, please ACCEPT so that I may be paid for my efforts. Thank you and have a great day.