I think she will realise what good grandparents you both are and her parents wont live up to much as you do such a wonderful job,i wouldnt worry to much.I can tell your grandchildren love you very much by what you do for them and that you actually want to see them.My mother in law doesnt bother with our children,always too busy which really hurts me,we only live round the corner,so believe me your doing a marvellous job and that will shine through.I'd be so proud to have grandparents like you for my children,so im sure your son and daughter in law must realise that,dont fret!!!