No one is grudging your wish to have some nice photos, but small children don’t get the memo about how they can behave like maniacs every other moment of the day, but not for this ten minutes when something important is happening. Expecting otherwise is unrealistic.
DH’s niece, who was about 3.5 or 4, was a flower girl at DH’s other sister’s wedding. Asked if she wanted to do it, would she be ok walking up the aisle holding her older cousin’s hand in front of Auntie K? Yes, v enthusiastic, all excited, adored the fuss about her dress, was a total pro at the rehearsal, it was in their local church she went to every week, so familiar, loved getting ready with the grown-up bridesmaids and her mum, hair done in a curly updo with fresh orchids (!) by the bride’s hairdresser on the day etc. Except she suddenly, halfway up the aisle, started roaring crying, threw down her basket of flowers, ran back down the aisle pulling the flowers out of her hair, banged straight into the bride and got snot on the front of her wedding dress, refused to come back inside and had to be consoled in the churchyard, and appears in all the photos scarlet, mutinous-looking and teary, or hiding her face.
This was in the early days of wedding videos so it’s all on there, including her tantrum in the churchyard which is quite audible through a shut door during the vows.😀
My point is that kids don’t get the memo about behaving well for just a few minutes for an adult priority.