There is no threat to my life, property or honour.

1) Is it permissible to pray behind a Sunni imam in congregational prayer?

2) Is it permissible to pray an individual prayer, within the Sunni brothers who are praying their congregational prayer but following their movements, for the sake of unity?

3) Does me praying my individual prayer within their congregational prayer invalidate *their* congregational prayer, according to *Sunni* fiqh?

I pray my Zohr prayers at school with the intention of individual prayer, but I pray it among the Sunni brothers in their congregational prayer and following the movements of their imam.

I used to pray in the corner of the room on my own, however, I opted to pray amongst them for the sake of unity. I also join their gatherings and discussions. Alhamdulillaah, upon making this decision I have helped my Sunni brothers to have a much more positive view about the Shi’a, resolved some of their misconceptions in certain issues, and overall gained a strong bond and connection with them.

However, recently someone has asked me why I have decided to join them instead of praying on my own as before, and I don’t wish to invalidate their prayers according their fiqh.

1- Yes, but you recite the Fatiha and Sura, because they are not reciting Bismillah
2- Answered.
3- No.