diff --git a/doc/environments/groupthm/groupthm.dtx b/doc/environments/groupthm/groupthm.dtx
index 66314b5..9eb2429 100644
--- a/doc/environments/groupthm/groupthm.dtx
+++ b/doc/environments/groupthm/groupthm.dtx
@@ -1831,7 +1831,7 @@
 %    \end{macrocode}
 % \end{macro}
 % 
-  % \subsection{Iterating over powersets}
+% \subsection{Iterating over powersets}
 % For generating the different variants of a theorem family,
 % we need to iterate over over the powerset of some list.
 % This is a collection of hacks that perform exactly this,
@@ -1936,9 +1936,9 @@
 % 
 % 
 %
-% \begin{macro}{\@@_declare_grouped_theorem_aux:nnnn}
+% \begin{macro}{\@@_define_theorem:nnnn}
 %    \begin{syntax}
-%       \cs{@@_declare_grouped_theorem_aux:nnnn}\marg{environment name}
+%       \cs{@@_define_theorem:nnnn}\marg{environment name}
 %       \marg{groups clist}\marg{theorem name}\marg{thmtools keys}
 %    \end{syntax}
 %		 
@@ -1947,7 +1947,7 @@
 %   command of \pkg{thmtools}.
 %
 %    \begin{macrocode}
-\cs_new:Npn \@@_declare_grouped_theorem_aux:nnnn #1 #2 #3 #4
+\cs_new:Npn \@@_define_theorem:nnnn #1 #2 #3 #4
   {
 %    \end{macrocode}
 % First, set local variables to default values and store current name.
@@ -2018,6 +2018,9 @@
 %   \groupthm_new_grouped_theorem:nnnn,
 %   \groupthm_new_grouped_theorem:nVVV,
 %   \groupthm_new_grouped_theorem:xVnn
+%   \groupthm_provide_grouped_theorem:nnnn,
+%   \groupthm_provide_grouped_theorem:nVVV,
+%   \groupthm_provide_grouped_theorem:xVnn
 % }
 %    \begin{syntax}
 %       \cs{groupthm_new_grouped_theorem:nnnn}\marg{environment name}
@@ -2025,23 +2028,14 @@
 %    \end{syntax}
 %		 
 %    \begin{macrocode}
-\cs_new:Npn \groupthm_new_grouped_theorem:nnnn #1 #2 #3 #4
-  {
-%    \end{macrocode}
-% Note that the next comparison depends on \pkg{thmtools} declaring
-% environments, and that \LaTeX\ handles environments called with the
-% |\begin{environment}| syntax by calling |\environment| subsequently.
-%    \begin{macrocode}
-    \cs_if_exist:cTF { #1 }
-      {
-        \msg_error:nnnnn { groupthm } { wrong ~ definition }
-          { grouped ~ theorem } { #1 } { already }
-      }
-      {
-        \@@_declare_grouped_theorem_aux:nnnn
-          { #1 } { #2 } { #3 } { #4 }
-      }
-  }
+\@@_define_multiple:nnnNNnn
+  { new, provide }
+  { grouped ~ theorem }
+  { ##1 }
+  \error
+  \@@_define_theorem:nnnn 
+  { groupthm_#1_grouped_theorem:nnnn }
+  { { ##1 } { ##2 } { ##3 } { ##4 } }
 \cs_generate_variant:Nn \groupthm_new_grouped_theorem:nnnn { n V V V }
 %    \end{macrocode}
 % We need this extra variant here for the generation of theorem families later:
@@ -2051,26 +2045,6 @@
 % \end{macro}
 % 
 % 
-% \begin{macro}{\groupthm_provide_grouped_theorem:nnnn,\groupthm_provide_grouped_theorem:nVVV}
-%		 
-%    \begin{macrocode}
-\cs_new:Npn \groupthm_provide_grouped_theorem:nnnn #1 #2 #3 #4
-  {
-%    \end{macrocode}
-% Note that the next comparison depends on \pkg{thmtools} declaring
-% environments, and that \LaTeX\ handles environments called with the
-% |\begin{environment}| syntax by calling |\environment| subsequently.
-%    \begin{macrocode}
-    \cs_if_exist:cF { #1 }
-      {
-        \@@_declare_grouped_theorem_aux:nnnn
-          { #1 } { #2 } { #3 } { #4 }
-      }
-  }
-\cs_generate_variant:Nn \groupthm_provide_grouped_theorem:nnnn { n V V V }
-%    \end{macrocode}
-% \end{macro}
-% 
 %
 %   The star variants of these that add the \texttt{unnumbered} group
 %   are straightforward:
diff --git a/doc/environments/groupthm/groupthm.sty b/doc/environments/groupthm/groupthm.sty
index 2bd03ad..865a70c 100644
--- a/doc/environments/groupthm/groupthm.sty
+++ b/doc/environments/groupthm/groupthm.sty
@@ -367,7 +367,6 @@
   {
     \groupthm_declare_group_rule:nnnn {#1} {#2} {#3} {#4}
   }
-  % \subsection{Iterating over powersets}
 \clist_new:N  \l__powerset_copied_clist
 \seq_new:N    \l__powerset_saved_seq
 \cs_generate_variant:Nn \clist_remove_all:Nn { N V }
@@ -417,7 +416,7 @@
         #1 { \tl_use:N \l__groupthm_name_tl }
       }
   }
-\cs_new:Npn \__groupthm_declare_grouped_theorem_aux:nnnn #1 #2 #3 #4
+\cs_new:Npn \__groupthm_define_theorem:nnnn #1 #2 #3 #4
   {
     \tl_clear:N     \l__groupthm_prefix_tl
     \tl_set:Nn      \l__groupthm_name_tl        { #3 }
@@ -445,29 +444,16 @@
       \l__groupthm_thmtools_clist
       { #1 }
   }
-\cs_new:Npn \groupthm_new_grouped_theorem:nnnn #1 #2 #3 #4
-  {
-    \cs_if_exist:cTF { #1 }
-      {
-        \msg_error:nnnnn { groupthm } { wrong ~ definition }
-          { grouped ~ theorem } { #1 } { already }
-      }
-      {
-        \__groupthm_declare_grouped_theorem_aux:nnnn
-          { #1 } { #2 } { #3 } { #4 }
-      }
-  }
+\__groupthm_define_multiple:nnnNNnn
+  { new, provide }
+  { grouped ~ theorem }
+  { ##1 }
+  \error
+  \__groupthm_define_theorem:nnnn
+  { groupthm_#1_grouped_theorem:nnnn }
+  { { ##1 } { ##2 } { ##3 } { ##4 } }
 \cs_generate_variant:Nn \groupthm_new_grouped_theorem:nnnn { n V V V }
 \cs_generate_variant:Nn \groupthm_new_grouped_theorem:nnnn { x V n n }
-\cs_new:Npn \groupthm_provide_grouped_theorem:nnnn #1 #2 #3 #4
-  {
-    \cs_if_exist:cF { #1 }
-      {
-        \__groupthm_declare_grouped_theorem_aux:nnnn
-          { #1 } { #2 } { #3 } { #4 }
-      }
-  }
-\cs_generate_variant:Nn \groupthm_provide_grouped_theorem:nnnn { n V V V }
 \cs_new:Npn \groupthm_new_grouped_theorem_star:nnnn #1 #2 #3 #4
   {
     \groupthm_new_grouped_theorem:nnnn