in season 1 despite him being weak when it came to his mom/sisters, somehow it felt he was still in charge of the situation, he was just put in a bind to choose between the two and people could relate to a guy being in that situation. but post leap Dev and his emotions are all over the place, unpredictable, cannot be relied upon. like said before Dev's redemption could have been acknowledging sona's struggle as a single mom for 6 years, even showing her flashbacks would have been more appropriate than Khatri track.
Todays episode just seemed to be put together since SS was out of town and everyone was going crazy to see them together. Maybe they could have easily shown Ishwaris character fallen ill on her trip and Dev had to rush to take care of her and then the mom and daughter could go back to their house. this would have answered for both SS and SP 's absence and then they could bring them in dixit house when SS was back from Indo.
Again seems todays episode was just pushed to give all of us some good devakshi moments. which if you are like me who has recently watched the past episodes, the moment was so rushed/ artificial and nowhere near the one's in the pre leap series.
but not to take away SS and EF acting. Seems they do the best with whatever they are given.