Does have a sibling at the university help with admissions?

My son is a freshman at Watson this year My daughter will be applying EA this fall. His SAT Math 2 score was 720 a hers is 680. However she got 760 on Chemistry and he got 720. Her SAT is 1400 - first time. His was 1470 second time. / She got 4s on AP World, US, Chemistry, Eng Lang and Comp, and 2 As in personal genetics and survey of calc through SUNY. Currently enrolled in AP Bio, AP Calc B/C, and macroeconomics, reading literature, statistics, and A&P 1 through SUNY.

She is also president of STEM CLUB, Captain of Science bowl team, officer in Key club (member for three years).
Prior to that she 2015-16 - International club, student ambassador, opera club, chamber choir, chorus, varsity wrestling + student volunteer at Match against Leukemia.

Summer - 15 Love volunteer
2016-17 - opera club, choir, key club, STEM for extraordinary girls (RPI), and science bowl.
Summer - 15 Love
2017-18 - youth court (Colonie)
She also be doing a shadowing program at locale hospital this winter after she turns 18 as part of the schools internship program.
She plans on going EA. Will her brother’s acceptance help her? Is Decker harder to get into than Watson ? She seems to have the better resume. What would you recommend moiving forward?

Your daughter will get in especially if she is a NYS resident.

Is that based on personal experience?

I agree, unless red flags in the common app essay, she will be accepted. Plenty of lower stats accepted. Good luck.

Seems like she should get in on her own merits. Why even suggest that her acceptance might be enhanced by her brother’s achievements when she has so many of her own?

If you look at the Common Data Set for SUNY Bing, you see that Alumni(ae) relation is “Considered”
https://www.binghamton.edu/oira/cds/cds_1718.pdf