GF wants me to give ang pao to her whole family every CNY, getting stressed

From my experience, giving ang pao to her parents and younger nephews/nieces is quite normal and a nice gesture, but giving to her siblings who are working adults is not standard. Married or not, you don't ang pao working adults usually. The real issue is money stress and communication, not the tradition. Sit down and talk honestly about your budget, that you also support your own parents. A partner who truly cares will understand and won't want you to overstretch. If she treats your financial limits as unimportant, that's a bigger concern than the ang pao itself. Set a comfortable amount and stick to it.

As a Malaysian Chinese girl, let me say her expectation is a bit much on the sibling part. Culturally you give ang pao to elders like her parents and to the young kids, that's the norm before marriage. Giving to adult siblings is not expected at all. But honestly the bigger thing is how you two handle money talk. When my husband was still boyfriend, we agreed on a small token amount for my parents and the kids only, and everyone was happy. Communicate early, don't wait until CNY eve then paham-paham. If she can't discuss money maturely now, imagine after marriage. Money conversations reveal a lot.