Cousin mad for not being able to come to wedding

I'm the wedding planner for my best friends wedding. They were going to have the wedding in this beautiful mansion in the woods, it is 4 hours from where we live and a lot more hours for most of the guests. Everyone was down to make the long drive since the place is just magical.

Sadly there was a death in the fiance's family (An elder uncle who was like a father to many of them but not too close to him), A LOT of his family will be attending the funeral in Mexico instead so that left a ton of people who did not rsvp. On her side her immediate family did rsvp, but one of the cousin's didn't. She said their business was really busy and they couldn't take time off plus it was hard to drive 4 hours with their 2 young kids.

With the funeral and the long distance of the venue the guest list went from 50 people to just 17. They decided it wasn't worth it to pay so much for the venue and instead came up with the idea of making this a destination wedding. They got 74% of the money back and that was enough to get everyone flights and hotels. We called everyone who had rsvp'd and asked if they could take a few more days off so they could come to the wedding in Hawaii. FLights and sleeping on the bride and groom and parents, everyone said yes and are now excited.

The cousin called me and said she hadn't gotten her new invite, I told her I didn't understand, she had told bride she couldn't come. She said now that it was in Hawaii they wanted to attend. I asked my friend and she said they were more than welcome to come but they had exhausted the funds and they would have to buy their own flights and hotels, well the cousin went ballistic. She's blowing up my phone saying how unfair it is that family is being excluded when some of the people coming aren't even family.

Bride said that was that. I don't want to put stress on my friend, this is her day but this girl is seriously annoying me. She keeps asking me to convince my friend to drop some people and include them instead or to ask them to take from the wedding budget for their travel and stay. What can I do to get her off my back? People are now taking sides and I want to plan in peace.