OP, I totally understand how hurt and disappointed, but please don't blame them. It's a totally natural process to idolise your absent parent, and feel protected of the one that pose themselves as vulnerable, but it doesn't mean they are rejecting the other parents, even if it feels like this.
My situation is different in that I am the mum. I separated from their dad when they were very little and he showed very little interest in acting like a responsible parent. His view of parenting is fitting the fun aspect of it around the life he built for himself. He expects everyone to make him feel good about being a dad. This means that for years, I had to take all decisions, responsibilities, care, and support them financially as he didn't give a penny in maintenance. I had to swallow my anger and agree to his manipulative way so that my kids could grow up thinking they had a loving father.
Still I thought it was all worth it until they turn about the age of your SD and suddenly, their dad became God and could do no wrong. As said, he wouldn't pay a penny, when challenged he always had the excuse of not having a penny to feed himself, played the whole sob story, begging me not to go to the csa because otherwise it would ruin him and then he wouldn't be able to see them at all and it would be all my fault...but of came Christmas, he spoiled them rotten, so they came back going on about how poor daddy had so little money but he loves them so much, he saved some money by not eating properly so he could get them some Christmas presents...and of course, they gobbled all of it.
If I tried, even in the most gentle and fair way, to tell them that it was exactly like that, I became horrible mum who was mean to poor daddy who tried his best. I was mean to want him to pay maintenance because I earned a lot of money whereas he worked so hard but wasn't as lucky as me.... I could go on.
All I can say is that as I'd hoped (sometimes cried), they did grow up and they did start to realise that a lot of what their father was telling them was fantasy. They are now 14 and 17, and yes, they are still protective of them. I think it is engross in them and that will never really changed, but they are not naive any longer. They now even laugh at some some of his sob stories, telling me 'well, you know how dad is with his stories'. I'm glad that they love him because that's what I desperately wanted, but I'm also relieved that they see him for who he is now.
All this to say, I expect the same will happen with your SD. In the meantime, however hard it is, try to be supportive and swallow your frustration as most likely, nothing you say to contradict them will be accepted as facts.