I’m best man at my buddy’s second wedding. Is it appropriate to open my dinner speech with “Welcome back everyone”?

Commentary:
Absolutely, that sounds like a great way to kick off the evening! 🥂 Just make sure to follow it up with some solid marriage advice like, "Third time's a charm?". 😄 Wishing the couple all the best on their new journey together! 🎉 #WeddingHumor