As a current bs student, I would say to just let them do what THEY are interested in. Adding on to other comments, just raise them to be good, hard working, motivated kids. Don’t push them to hard. Their childhood should not be focused and revolved around on getting them into a good prep school. Honestly, I think if my parents had put me in so many things at a young age, I would have resented them when it came time for the admissions process. For all you know, your children won’t want to go to boarding school. Not trying to sounds harsh, but for goodness sakes your child is in the 1st grade. You can though get started on community service as a family. Volunteering to make lunches for the homesless can be a good activity for younger kids. Look online and through your town/city website because they will often have opportunities listed.
The MOST important thing and I can’t stress this enough is to raise them to nice, compassionate, motivated kids. The rest will workout for itself. Their whole life cannot just be about bs. Your kids might not even want to go to bs. Kids have different wants and needs and you shouldn’t force them into anything w/o their say- and that means not feeling any pressure from you. Everything they do from a young age should not just be about looking good on applications. I truly do hope that you take this into consideration. If you have any questions feel free to pm me:)