Dear Sharan,
I think this question is a modified version of your previous question in the thread entitled " Take over of a company - should the employees ask for Good will? ". It can not be a statutory obligation on the part of the previous employer. If the take over does not signify a distress sale out of a hostile take over, well, such a move by the previous employer, either voluntary or at the request of the employees would be an indication of his magnanimity as well as long run cordial employer-employee relationship in the past.