There are many older threads on this case. It's explained and shown on video that they were there to have a memorial celebration of the birthday boy's life. There is video taped by the same station that edited out the parts they didn't want people to see. Darlie was crying. Her face was red and her nose was running- not faked crying. The plan was to release balloons in memory of both boys on the one's birthday at the cemetery.
Her SISTER brought a young child and 2 cans of silly string.
She and other family members consoled Darlie and convinced her that the boys would want them to be happy and celebrate their lives.... The sister started spraying the silly string on some of the balloons and Darlie did too. Darin had Drake there, no one objected, all of them were laughing and talking about the boys' cute things they did.
It was an edited video in that the initial sorrow and crying which seemed very genuine to me was edited out. I've seen a ton of faked crying in my profession ( also, in other cases, as Patsy Ramsey was probably the pro fake crier of all time) and Darlie was depressed looking when she arrived in a baggy shirt, little to no makeup or grooming and casual shorts, and was not smiling or cheerful when she was first at the cemetery.
Lastly, they did not spray the silly string on the graves. It's a memorial which was and is flat to the ground, and they sprayed higher than that, in the area of some balloons tied nearby.
Edited to add a thought- IF Darlie had staged the " silly string' part for media, I believe she would have done her hair, had on 3 layers of makeup and been dressed quite differently. It was the 90's and young women were flashy in Texas.. I'm a woman, and a Texan.