How do we suggest guests buy plane tickets that can be refundable?

After all of the travel issues of the past three years, I think anyone who books non-refundable travel is making a huge mistake. That said, if you think there's a chance that your wedding might have to be rescheduled last minute, you have an obligation to inform your guests up front.

Do this when you send the save the dates (since you may have to change the date!) and again when you send the invitations. If you have a wedding website, that would be a good place to do it, but not everyone reads those, so you should be more proactive with your communication. You don't need to say, "Buy refundable plane tickets." But you do need to clearly say that your wedding date is tentative. They should be able to make their decisions about booking travel after that.

Almost all airlines if they dont give refunds will at least allow for flight credits that can be used for other flights. I would mention it on the save the dates or in an insert so people can evaluate whether they want to commit to taking time off work/traveling knowing it might be rescheduled