如果在美持 B1簽證期間先轉為學生F1簽證，等排期適合再結婚遞I-130是否可行？
-Yes, but she still needs to wait for at least 90 days (90-day Rule) and then, file the change of status. If she can get the F-1 visa to enter US, that will be ideal. Thus, she can get married after 90 days and wait for the priority date is to be current to file I-485 during her study as an F-1 stduent.
這樣多重轉身份是否會引起其他問題，
-It should not be a problem if she files the status change applicaiton after 90 days later after she enters US using B1 visa.
反而需要更長時間？
-It may take a longer time to get the F-1 application approved.
Normally, B1 status allows her to stay in US for 6 months, so if the priority date becomes current during this period of time, she is OK to file I-485. From recent few of years, F2A category 排期 is very short. Most of time, the applicant can file I-130 and I-485 concurrently.
