I do not think BJP would be more friendly with BD than congress, this is may be because of coming election in India, or may be BJP is pissed up that congress is so openly playing with BD. Perhaps, had BJP been in the power, they would have executed India's notorious plans in more subtle manner and successfully than Congress, therefore, BJP is arngy.
I think India has a specific foreign policy on BD irrespective of which party is in power in India unlike us; I think India's foreign policies on BD is determined by their intelligent agency RAW, not by political parties like Congress or BJP. And that is the right way I think, I mean the foreign policy should be same, but strategy to implement those policies can be different by different political parties. If BD's foreign policies toward India were regulated by our NSI/DGFI/intel , we would not see BAL and BNP are fighting against each other over India, and there were no Dalal or Razakar calling issues. In PK, their foreign policies toward US and India are mostly controlled by ISI, where PPP or Muslim League just play in different way for the same goal, I think.
What BJP is pissed off, may be, is Congress has failed to hide its plan that BJP could have done in different way but the policy/goal is same.