V tries to harm T..
U helps Raghav save T..
U becomes the good guy in Sia and Raghav's eyes..
S and R therefore believe whatever U tells them and they feel safe being honest in front of him.
When U tells them V knows where Jhanvi's family are they instantly believed him, AND, most importantly, R said their new address in front of U! - U was listening very carefully to the address and also we didn't hear what V said, for all we know he could've simply been reminding U to put their plan into action and that's probably why U said yes sir, as in I'm doing it right now..
Doesn't it all seem like a thought out plan by V in order to find S's family and use them as blackmail against S?
U's whole story about his brother is a very convenient way to gain S and R's trust..
Whether it is or isn't a plan I'm surprised they trusted him so easily..