A musafir will perform salah with qasr if he offers it individually or with the congregation of musafirs i.e. instead of four rak?ah of fardh he will offer only two. But, if he performs salah behind a muqeem (on station) imam, then he will offer full salah (four rak?ah). There is no need to perform salah with separate congregation; rather they should follow the muqeem imam.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband