We had a group of people being denied boarding in Croatia, because of the lack of proof of their stay. In Croatia now they have to ask for entry stamps, and save boarding passes together with hotel bookings and other recipes to prove their stay. I always suggest to the people we help that they start by checking out channel out, and especially this video on binders and how to structure yours. They just need to see proof of you being out of Schengen enough to allow you to board, and sometimes they don't see that and they are not willing to take a chance. I hope everything works out for you in the end, and if there is anything we could potentially help you guys with, let us know. Send us a message through Facebook or instagram. Take care and good luck :) https://www.youtube.com/watch?v=-zlOJj_u4sk&t=1s