I believe you asked the same question elsewhere in these the treads and forums.

I understand you are exploring the possibility of taking advantage of Malaysia's super-cheap business-class fares from KL to AMD, ATQ and TRV. Though probably not Trivandrum because of the low number of BAEC tier points you'd get.

I'm afraid you're going to have to lay out a little more cash on a night stop. Without an Indian visa, or the right passport, you won't be allowed on a flight to India at KUL. I doubt that you'd even be able to purchase a round-trip ticket incorporating a back-to-back return.

An international B2B is very unlikely to qualify as a legitimate transfer at any Indian airport, making an airside transfer very unlikely. I think it was hotly discussed for AMD, fuelled by a crazy SQ fare to Houston: the consensus was that it was that rather than risk a B2B on the SIN AMD and AMD SIN sectors, it was smarter to get a visa and accept kicking heels in the airport, or an overnight in the city.

By the time you get through immigration and customs, up to departures and through the security check the check in desk will be long closed. You need an airport issued boarding card.

Air India staff there were a great help at Amritsar facilitating our connecting from Birmingham UK to Delhi in time for our domestic flight. Not their fault that flight was then delayed five hours, but that's another story. However, I'm pretty sure that even a legitimate transfer between international flights has never been attempted there.