Medical examination delay affecting interview

[BombayParents]

I applied for IR5 for my parents. NVC sent case complete to Bombay consulate and got the interview dates also for both my father and mother. My mother got through the medical and is about to appear for the interview. My father has been sent for secondary screening for additional test for TB and had to cancel the interview. I believe the additioanl test will take 2 months to get the results. Assuming he passes the secondary medical test, I believe that the medical results are valid only for 3 months from the date of medical examination, of which two months will be wasted in waiting for the results. That hardly leaves one month to get an interview date and leave for USA. If I dont get the interview date during the one month window, will my father have to repeat the medical all over again ? In the meantime, my mother would have completed her interview and the whole situation will become messy.

Any advice / suggestion / shared experience is welcome.

Thanks.