Amabal to Kalka you can get a train and from Kalka to Shimla there's a toy train and even you can stay at for a night and then leave to Manali through a bus. As you told you are traveling with your parents this is kinda breaking the journey so that it won't be too hectic for them.
Hey Sourabh, The best road to take from Delhi and the safest is .... Delhi - panipat - karnal - kurukshetra - markanda - rupnagar - Bilaspur -sundernagar - Mandi - Bhuntar - Naggar and then to manali .... This will be the best to go on a road trip ... i also have been on this road and s good to take ... Happy and safe Travelling Bro!!!
Hey Sourabh, just checked it ... roads from anadpur sahib is not that good ... and go to manali via naggar after kullu ... thats better ... apart from that the entire stretch is good ... few small patches are not good .. and that is everywhere on mountains ... so don't worry mm go ahead ... be slow in driving ...