I think it's time to move this topic to RWI as this is getting involve into some religion and parent's last will.

I basically read everyone's comment (useful ones). To sums up;

Once you convert yourself into Islam, you NOT allow to touch joss stick and do the Buddhist chanting and stuff. The only thing you can do is to observe. Correct me if I'm wrong.

But bring back TS's problem, as the eldest kid, you failed your parents by not holding the joss stick (if your parents are superstitious enough), not doing the normal Buddhist chanting, pray and bow upon them every death anniversary (of course you can do it in private. who would know right?)

Moreover, you're not ALLOW to carry your parents' coffin to their grave because you only allow to observe, which is a SERIOUS, I do mean it, very offensive action to Buddhist's "follower" (cause your parents are Buddhist). Ask your parents if they are okay if you not going to carry their coffin, but before that ask yourself if YOU should be asking them this question after so many years of cultivation on you.

If you REALLY and MADLY in love with this Malay girl and you don't want to break your parents' heart, I suggest you go to places where their marriage system is recognize worldwide. (Just saying, don't know if there's such powerful country exist..)

Good luck and hope you can find a perfect solution for your dilemma.