It will be a cold day in hell before someone other than my child tells me who I can and cannot invite to my child's wedding. I'd love to see my future DIL's mother try it.
Easy to say when your son is marrying a woman who is willing to compromise, who does not have preconcieved ideas of what "her" wedding is going to eb, and whose parents are not bent on ensureing that their every detail is adhered to while your son and his family are along for the ride.
One thing I learned a long time ago is that when we are on the outside looking in at wedding planning it can be very clear to see how the marriage will be "run." If the couple is courteous of both sides of the family, and both respect the traditions, finances, etc of the "other" side, and can manage to include both families in planning whiel still maintaining their own identity, you will have a peek at how the relationship between each family and the couple will flow. WHen one side, either brides side or groom's, has a voice that must be adhered to regardless of the concerns of the other, you will see how the dynamic is going to be moving forward.
It is very easy to say what your reaction would be when you are not wearing those very tight shoes someone else is wearing. I am very lucky to be blessed with children who married people who respected us, but I have been an uphappy observer with family members who were not as lucky as my DH and I. There is no graceful way to put your own foot down when it is going to land on your child, and once that occurs rebuilding the break is very complicated, if at all possible.
A wise woman told me years ago that
1: She would never lose her son over her DIL
2: We all are given a finite number of bullets in this life so when you choose to use your ammunition, make it count.
I have never forgotten her advise, and to this day I am very careful about my words and my actions with my children and their spouses. If they ask I will share my opinion. If they do not ask I think long and hard about using that bullet to make my point.