My problem is that I need to start new chapters on the same page if there is still space available. I use the scrbook class.
As far as I see I have two solutions.
1. Change the class, i.e. to scrarticle and lose out on having chapters
2. adding selectively:
\begingroup
\let\clearpage\relax
\chapter{My Chapter}
\endgroup
or I can do the same for the whole document with:
\renewcommand{\clearpage}{}
But if I do this Latex is all fact up and kind of ignores its nice visual pleasing features, see the picture. I need to mention that I use for each chapter and their sections a new latex file, while adding them with \input into a main document.
What am I doing wrong. If I need to resort to manually adding spaces at the end of the last chapter, how much vertical space should I add?

style=sectionfor the\chaptercommand and alternatively the declaration of a new sectioning command. – esdd Aug 12 '19 at 16:06