I have this theory on How blackmailer is threatening Saloni.
Vrinda cooks food for Nahar's family and around kitchen all the time. May be blackmailer has threatend Saloni if she does not do what BM wants she will make vrinda poison the whole family. So saloni is doing all this to protect her family.
It is very possible jiji is working with vrinda and shibu may be vrinda's brother or relative.
post your comments.