If she loves this college, go with it. CGPA is a going to be a large % for SFT selection.
There is also something great about being the firsts, not only for CC recs., but personal leadership.
If she loves the large det and that college, she needs to go there. Quickest way to not be commissioned is doing poorly at ROTC and college. Going to your second choice will play into that equation.
If she loves the college of the smaller det, but fears attending because the big det is in place/recognized, remind her ROTC exists to create leaders. She will be able to shine and gain experience with a new det.
SFT selection is national, and they place a lot into the equation. Size of the unit does not have a % awarded. PFT does. GPA does. Rank does.