\documentclass{article}
\usepackage{glossaries}
\newacronym{child1}{Child 1}{Child 1}
\newacronym{adult1}{Adult 1}{Adult 1 \glsentrylong{child1}}
\newacronym{adult2}{Adult 2}{Adult 2 \glsentrylong{child2}}
\newacronym{child2}{Child 2}{Child 2}
\begin{document}
\Gls{adult1}

\Gls{adult2}
\end{document}
