Unless there are knock down, drag out fights at the table I'd just go with the flow and let everyone sort themselves out as they seem to be doing already.
Perhaps you could have a quiet word with your son and let him know carefully the source of his children's discomfort so he can gently discourage her clinginess in front of them. I would imagine her clinginess stems at least in part from her feeling uncomfortable, it must be daunting to be in a group with inlaws and exes as well. Let her know you think she is a nice person :-)

Thank you for your advice. We have tried to make them all comfortable. My husband and I have decided maybe we should just leave town on holidays and let them all do what they may. We have a graduation party this weekend. I have spoken to our son he thinks we should just do as we have always done and get over it. His children are 18 and 23 and right now are not happy. I know that they will all get over the hurt of the divorce. It just takes time.
Mary