It all depends on your situation. Will you be taking care of them after you get married or will you leave them? If your leaving them give them a small amount, but if your there helping with the monthly bills give them nothing! It's outdated now, just another way for people to get money out of your pocket.
that's what I do mate. I use my wife's home address, well my home address when I'm here lol. If your living or staying with her use that address. That's what I used on my COE.
If your not going to live with anyone 'wife/family' just put your hotel in that you will be staying at. There looking for an address after you've quarantined
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