Welcome!
One bit of perspective to keep in mind is that your DC is in a very small pool of grade-peers. With only 120 total students, one would expect about two or three to fall above IQ 130. Even a more generous cut score would probably only net fewer than a dozen students. Once you throw in a second measure, the expected number of qualifying students plummets even further. With achievement at the 99th %ile, she is one of (statistically) 1.2 students in the grade at that level, if your district is representative of the national norm group. So it's hardly surprising that the district can't find enough students to form a cohort.
That being said, it might make more sense to focus advocacy on individualized educational supports, either in the classroom (curriculum compacting, test-out, differentiated texts, etc.), or through other approaches, such as single subject acceleration (cross-grading) in her area of greatest strength.
