To me it seems so.He may be the one responsible for the Poosh killings also.It was rumoured Rajveer was HH's illegitimate son so his crimes may be stirred by jealousy. It is not unusual to have illegitimate kids envious of legitimate children who enjoy all the rights they long for. Rajveer's anger is focused on Aditya as we saw in the track where he was visible.It is possible he may have caused the accident to get rid of Pooja seeing how happy Aditya was with her. Yash was merely the collateral damage.
Now he cannot bear to see Aditya happy in second relationship so the serial attacks to get rid of him and Zoya.
The parents have some dark secrets but probably not sinister enough to kill their own children.They hedge and are suspicious as they do not want skeletons tumbling out of their cupboards.
To my thinking it is Rajveer behind all the crime in BP.