Baggage check through on same PNR but different classes
 

First leg of the journey HND to SIN is JAL first. I plan to check in 2 x 32kg baggage, arriving SIN at 17:25.

Within 24 hours, the following morning at 06:00, I will start the second leg SIN to KUL and then KUL to LHR, but both in MH economy which only allows 1 x 32kg piece.

Both are booked in the same one world redemption ticket, in one PNR.

Questions:

1. Will I be able to check through all my luggage to LHR at HND first class check in desk?

2. Because of different classes, baggage allowance is different. Do I need to buy extra luggage for the MH legs from SIN to LHR via KUL?

Thanks a lot!