回複：485副申請人的表格, 需要主申請人簽字嗎?

It depends;

If the applicants are less than 18 (or you prepared the form for them), then you need to cosign. Otherwise, not necessary.

If you want to keep track of the status for them, you need to submit the G325 to act as representative for them.

I did the both ways, so I have an access when I need to handle any issues with their applications on thier behalf.

Just for reference!!