Also, The Girl Scouts explicitly rejected a large donation from an anti-trans organization: https://www.seattlemet.com/news-and-city-life/2015/06/donor-says-girl-scouts-can-t-use-100k-gift-for-transgender-girls
Girl Scouting is for all girls. Trans girls are girls, so they belong in Girl Scouts.
FWIW, the Scouts–formerly Boy Scouts–now also have girls and LGBTQ+ kids. They’re a fundamentally more conservative group than the GSA though.