Get your child to a safer state. Then report it to many agencies and let each agency know many but NOT all the agencies that you have reported it to. Make sure they know that there are other unnamed agencies.
Out of compassion for the other children that may be involved. If you can figure out how, let the families of the children know that you suspect that grooming has been going on with your child. Use the word "suspect", so you can't be attacked for slander. Andy decent parten will take warning.