I think that Kaajjal won't be able to get Raju to say that he is Dev, cause he might not know it either...Since Kaajjal has to go back to Mumbai or her dad would get suspicious, she would take Raju along.....For raju to go....she has to tell him everything and how she really needs his help.....he might then agree to help her......he will enter the Singh family as dev.....everyone would be shocked to see him specially Ameesha...........
Second: since Kaajjal has to go back to mumbai....she will not taking Raju along....as mentioned by someone, Kaajjal will find out that Ameesha and karan are partners in crime...Then she might go back to Rajgani and tell everything to Raju and ask him to help her out....that he is the only person that can really help her.......Raju will go and try to help her out...