It doesn’t sound unusual, OP, but it isn’t great and you have good advice above. I know it is difficult and I think you can steer DD onto a good path.
But, gently - please bear with me, because I know parents are caught between a rock and a hard place - what’s all this about the mums doing the work for the competition? Sure, if the teacher turns a blind eye, a DC turning in a parent’s work is likely to win.
But that parent isn’t helping their DC to grow up.
They are teaching that winning by foul means is the most important thing. Most importantly, and I say this as an (HE)academic, it is bad for the mental health of the DC. Children need to learn that they can rise to (appropriate) challenges!
The ones who think winning is more important than doing become the many having MH crises as undergraduates. The HE Board is full of these threads, and the Mitigating Circumstances panels at even our best universities (I did a long term on one of them) deal with huge numbers of them.
I appreciate that you came from a good place and hoped to give DD the joy of victory, but she and the other girls will be happier in the long run if loving parents think more about helping their children to grow up.
Obviously this requires that teachers drop the faux naivete and stop awarding prizes for adult work. Possibly this can only be achieved by banning these competitions.
Take care and best wishes