As long as it's not a wedding, you don't have to give a red envelope to attend or not. Only formal weddings need to give red envelopes. Of course, if your other colleagues are interested, you can only go with the team.

But actually, I just don't participate. If you don't go, you don't have to give a red envelope. Just find an excuse to say that you can't attend that day and congratulate you on your happy wedding.

If you are worried about the relationship at work, find an excuse to say that you will attend your elder's birthday party that day and can't attend his thank-you banquet. You can take a good step down.