Hi Prasenjit,
First of all, my apologies that you've had to wait for an answer to your question.
For your benefit and the benefit of others facing a similar dilemma, just some quick feedback based on my experience: in general, I am a fan of proactivity on the waitlist, so your energies might be best spent sending Broad relevant updates, letting them know that you are passionate about their program and showing them what you're doing to become a stronger applicant. In my experience, schools are often resistant to being pressured into making a decision, so telling them you have another offer might not work in your favor. However, showing your love, always bearing in mind the school's waitlist instructions, never hurts.

Hope this helps,
Margaret Strother