Merging OBJs together, for real

No.525520 ViewReplyOriginalReport
I'm so mad right now, I've scrolled over 9000 Google results, but can't find an answer to what seems a really simple job.

I want to merge a huge amount of tiny OBJs into one single huge OBJ and keep all the textures, I don't want to group them so they give the illusion they've been merged together but actually are not, there needs to be ONE single mesh, an actual fusion. Pic related.

Each piece have a tiny overlap (done on purpose) to ensure that they touch each other leaving no open gaps between them, the problem with most reconstruction algorithms I've tried (ie. Poisson), is that it tries to fill everything, even holes that are supposed to be left intact, not only the parts that touch/overlap, not to mention I couldn't find a way to keep the textures.

What do you suggest me to do? Doing it manually is not a an option, there're just too many teeny tiny pieces.
Bonus points if it can be done with a free software, thanks all.