\documentclass{article}

\usepackage[enable-debug]{expl3}

\ExplSyntaxOn
\debug_on:n { all }
\ExplSyntaxOff

\usepackage{mkessler-groupthm}

\DeclareTheoremGroupRule {dagger}{before}{star}
\DeclareTheoremGroupRule {starred}{higher}{dagger}

\NewGroupedTheorem
  [
    group = {big, starred, dagger}
  ]{dlemma}

\NewGroupedTheorem
  [
    group = {big, star}
  ]{slemma}

\NewGroupedTheorem
  [
    group = {big},
%    thmtools = {sibling = insection}
  ]{lemma}

\NewGroupedTheorem
[
  name=Proposition, group = {dagger}
]{dproposition}

\NewGroupedTheorem
[
  name=Proposition,
  group = {star}
]{sproposition}

\NewGroupedTheorem
[
group = {dagger, star}
]{test}


\GenerateTheoremVariants[ group = {star, dagger} ]{example}

\DeclareTheoremVariants{example} { !s !t+ }
{
  \IfBooleanT{#1}
  {
    \AddTheoremToGroup { star }
  }
  \IfBooleanT{#2}
  {
    \AddTheoremToGroup { dagger }
  }
}

\begin{document}


\b{hi}

\begin{dlemma}

\end{dlemma}
%\begin{__example__groups_dagger_star}
  test  
%\end{__example__groups_dagger_star}

\def\ex{__example__groups_}

%\ShowHook{groupthm/groupsort}
 

\begin{example}
  test
\end{example}

\begin{example}+
  test
\end{example}

\begin{example}*
  test
\end{example}

\begin{example}*+
  test
\end{example}

\begin{example*}
  test
\end{example*}



  
\end{document}