Couple says

We want our wedding to be disruption-free so we can focus on the grace of the sacrament.

Parents say

This is about family, so we must invite everyone, including the little ones.

Two excellent values are competing here: wanting to respect the sacramental solemnity and wanting the sacrament to be witnessed by the broadest reach of your families. First, let’s celebrate these two values.

Good for you for focusing on the sacramental meaning of your wedding. And good for you for not wanting an “adults only” wedding either, where no one under 18 is welcome. School-aged children, especially middle and high schoolers, need to witness sacramental weddings. As the camera in Fiddler on the Roof’s wedding song, “Sunrise, Sunset” pans the large gathering of family and village, it rests for several long, magnificent seconds upon the intent gazes of children just this age. They, like everyone, are there to absorb, to remember, to dream, to support and, if necessary, to remind.

And it’s also good to want to include even those very little children who would not only be clueless about the moment’s significance, but who would also not hesitate to hijack it with a tantrum. Why? Because even in their disruptiveness they represent one of the essential purposes of the sacrament of matrimony: to lovingly welcome and nurture all the beautiful mess that is a new human life. (CCC 1601)

So imagine this: Just as you are exchanging your vows a two-year-old screams, “No! No!” as she is being quickly removed from the sanctuary. Seriously, little ones like that can be a problem. You can hope that most parents of children that age have the common sense and courtesy to sit close to an aisle and an exit. You might want to have your usher encourage them to sit in such a location!

Consider this: If your concern about this risk is acute, maybe hire an on-site babysitter for these little ones and blanket advertise this “complimentary service” in your invitations. This would not only provide a welcome respite to at least some parents, but it would also indirectly signal a sincere, loving plea that your wedding not get unnecessarily disrupted.