Dynamically position of a flowfram box on the same page as the heading

Question

i want to position a flowfram-box dynamically on the same page as the caption. So that the box is allways next to the a certain heading as the document is growing.

In my following example the boxes are layong on top of each other on the second page.

How can I position the boxes only one time next to a certain heading?

\documentclass[10pt,a4paper,landscape]{article}
\usepackage[utf8]{inputenc}
\usepackage{caption}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{flowfram}
\usepackage[left=10cm,right=1cm,top=1cm,bottom=2cm]{geometry}
\author{}
\title{}
\setcounter{secnumdepth}{-1}
\parindent0pt
\twocolumn
\begin{document}
\section{HEADING 1}
\subsection{HEADING 1}
\newdynamicframe[\thepage]{0.33\textwidth}{\textheight}{-240pt}{0pt}[Lastannahmen]
\begin{dynamiccontents}{Lastannahmen}
        next to heading 1
        only on the page of heading 1
\end{dynamiccontents}
\lipsum
\newpage
\section{HEADING2}
\newdynamicframe[\thepage]{0.4\textwidth}{\textheight}{-240pt}{0pt}[Lastannahmen2]
\begin{dynamiccontents}{Lastannahmen2}
next to heading 2
\end{dynamiccontents}
\lipsum
\newpage
\end{document}$

Answer 1

I don't think flowfram is really suited to this type of thing. I think you'd be better off just putting the required text in the margin. Like this:

\documentclass[10pt,twocolumn,a4paper]{article}

\usepackage[twocolumn,landscape,a4paper,hmargin=2in,marginparwidth=1in]{geometry}

\usepackage[utf8]{inputenc}
\usepackage{caption}
\usepackage{lipsum}

\setcounter{secnumdepth}{-1}

\newcommand{\sectionwithbox}[2]{%
 \let\orgsectionmark\sectionmark
 \renewcommand\sectionmark[1]{%
   \marginpar{#2}%
   \orgsectionmark{##1}%
 }%
 \section{#1}%
 \let\sectionmark\orgsectionmark
}

\begin{document}

\sectionwithbox{Heading 1}{Stuff in box next to heading}

\subsection{Sub-heading 1}

\lipsum[1-4]

\sectionwithbox{Heading 2}{More stuff in box next to heading}

\lipsum

\end{document}