Add more images to slider

I really like this theme a lot. I went through all the threads and I noticed that questions don’t really get answered by the parabola team, is that correct? Well, I hope to get an answer to my question obviously :)…

I would like to add more images than the Parabola slider (5) provides. I made posts and added a specific category to them, and put in the featured image with the size of the slider. I tried the option of the specific post and the option with the specific category. Neither works. I don’t want to publish the posts because for me it’s just a work around to get more pictures in the slider (10 in total). Did I do something wrong or do these options only work if you publish the posts? Does anybody have another suggestion to add more images to the parabola slider on the presentation page?

[if not, I would like to do a feature request to be able to add more images to the slider up to 10-15.]

All help would be much appreciated!

Kind regards, Sandra