So, B in her naivety has sent it to C. C has then informed parents/police
So, its in the best interests to the public to prosecute all is it?
So A, B and C get arrested and have their phones downloaded. The court will ask if there is any other evidence to suggest that this is a pattern between them - so the police will have to seize computers/laptops at their address and have them downloaded.
The length of time to send these away for forensic downloads is months & months and the cost is huge - and during this time A, B & C will remain on police bail. We will have to consider safeguarding during this time until there is a court appearance - so they will be excluded from school.
As a parent of A, B or C you would want the best for your child and not have to put them through a court case - so an out of court disposal will be more applicable i would suggest in this case - or would you suggest that the parents thoughts are not taken into consideration on this case and we should just prosecute.
I really don't think that this is in the public interest or the interests of B & C to go down this route. You will have an argument to prosecute A - but not B & C