This may not be a popular comment, but I'd skip the testing for now. See if there's another way to get what the girls need without putting them through testing to prove their PGness.
Why do they need the testing? Is it to get into a program that would benefit their educations? Is it to joint DYS? Is it to improve the level of the work they are doing in school? Whatever the reason for the testing, is there another way?
I agree completely with this comment.
I'll add that if it was ten-year-old me and I was told I was going to another state for one reason, got there, and was then suddenly told that the real purpose of the trip was to force me to do something that made me very uncomfortable to the point of biting my nails until they bled --- well, I would have seen that as a major betrayal. Honestly, I suspect that my feelings of betrayal would have affected my test scores, too.
