Answer:
(Fatwa: 1446/1375=B=1430)
In this case, turn head for salah at two rak?ah and join the congregational salah. Later, you should perform the four rak?ah again, the already performed two rak?ah will be considered nafl.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
