Is It rude to not have nieces/nephews at an adults only wedding?

We are 4 months away from our wedding, and we made the decision to have no children at it a year and a half ago. This decision was made with both our parents input saying it would be fine if no kids could attend.
Yesterday, my mother asked about having our niece in the wedding for photos.. and flipped out when we basically said no. We had discussed our niece when we made the decision to not have kids (1.5 years ago), and my mother in law said it would be no problem and not to worry about not having her there. NOW, she’s going to try to guilt trip us into it. She mentioned having someone drop the child off for pictures (since that’s what she really wants, her to be in photos she could frame). However, I’m a little wary of having someone drop off a 2 year old within a 5 min window of doing family photos, at our destination venue then taking them back right after. I worry it’s a recipe for disaster and we said no kids... right?!

i’d like to hear your guys’ thoughts? Are we being ridiculous? Or should we consider it?
My biggest annoyance is why this is just now being brought up after I have told many of my very close friends they couldn’t bring their children to our destination wedding - which is no easy feat to find childcare for.