Convert multiple files together to fit on 1 BR disc

[Toro]

Hi, I want to convert multiple videos to fit on a 25GB disc. If possible with the creation of a menu and with a freeware program. The quality is not my major concern, because I will be burning 10-15 hours of video to a disc. I've tried some programs, and only power2go platinum and leawo blu-ray creator seem to possibly be able to perform the task I want, but on both I can't test if it really works the way I want it in the trial. Wondershare and dvdfab didn't work for me. Handbrake also not, and I tested some more, but i can't remember all the names. Most topics on this forum are about shrinking 1 file, then it would be doable to do math on file size, but with 19 files it's hard to calculated the individual settings to get to the right size. Also a menu will be a plus, but if that's not possible, I will accept writing data blu ray discs.
Thanks for the help!

/Edit Freemake video converter has an option to create blu ray's, but I get an error there that the iso size is too big, even when I just select a 45 min video file.

/Edit2: MultiAVCHD seems to be able to convert them, but I can't add text to go along with the the thumbs, and the thumbs are not showing. So the only option is to change the filenames?