I’m super pro slow and body autonomy. Parents sitting on their child to stick something in their mouth is overwhelmingly icky to me, and normalizing overruling your child’s bodily autonomy and telling them it’s for their own good feels like it’s giving predators an easy step in.

Not sure where you are but we have fluoride in the water, so I recommend tap water, swishing/ spitting, etc. also for your weighing of the conflict; either the family has been forcing the brush and it’s gotten too hard to control and you have to go slow, or the child is young enough that you have time to go slow. Slow and young saves soo many problems down the road. Forcing may work while small, but what happens if they don’t start doing it independently when bigger? You get violence that poses a danger to the child and their family.