Depending on the boarding school. Some schools need all international students to take the TOEFL . Some schools do not if your child is going to international school. Both my kids didn't take the TOEFL for PEA and Milton.
For boarding schools, they will definitely need to take the SSAT (not SAT). If you are applying to higher grades (G11 and above) , some schools will require the PSAT or SAT.
If your daughters are residents or US citizens, then she can go to a public school and they won't need to take the tests.