Hi Elaine,
Usually for the malays, the parents pay for the wedding. So the angbao they will keep to cover the costs. But if there is any extras, it's up to them whether to give you or not. But those guests who give to you directly, it's up to you whether you want to keep or give to your MIL.
But usually for the malay guests, they will give the angbao to the parents, it's a courtesy to see the "tuan rumah" (direct translation: House Owner) AFTER makan (for chinese: before makan)even if they don't know the "tuan rumah" directly. But err for me hor..even though i malay, i'm not comfortable with this, so heheh..i would rather "salam" the bride / groom.
Usually for the malays, the parents pay for the wedding. So the angbao they will keep to cover the costs. But if there is any extras, it's up to them whether to give you or not. But those guests who give to you directly, it's up to you whether you want to keep or give to your MIL.