The following steps are acceptable. The principal investor, spouse and qualified children can apply for their conditional permanent residency visas at the U.S.consulate. Once they arrive in the U.S. The child who is already in the U.S. under F-1 student status can apply for an adjustment to conditional permanent residency status and file the forms with the YSCIS without having to leave the U.S. Our law firm has represented many clients in the same situation and without complications. But remember every case is different.
That could be possible, but it would require proper notifications and other planning best done with the assistance of immigration counsel.