Separation Pay

Our manpower agency is closing due to financial losses. The owner of the dental plant where our workers served for more than 5 yrs announced a month ago that they will transfer all our workers to the other existing active agency. A month ago our workers signed a consent to be transferred but a select few are now refusing to transfer to the other agency. Are we obligated to give these workers their separation pay even though we did not dismiss them and there was no interruption in their service? They also signed a quitclaim with us in the office 1 month ago. Last payday the dental plant refused to release their salary unless they sign with the other agency. Our contract with the dental plant ended 2 months ago yet our workers continued to work for them, does that make the dental plant their new employer? I hope you can help as I am very confused and don't know what to do. Thank you very much, and more power to you.