Cousin got married because she couldn't leave the annual meeting. How to tell your uncle and aunt by SMS? Should I say a red envelope in it and ask my parents to give it or something?

Direct telephone communication is recommended. Sending text messages can give people a perfunctory feeling.

Generally, I will understand that if your parents go, you will go. Just bring the gift money your parents gave you when you went.

As for communication, do you want to explain whether parents should bring red envelopes? You can ask your parents for advice. Different places have different customs.