diff --git a/sddi-base/Dockerfile b/sddi-base/Dockerfile
index a053b3d..61dc6f1 100644
--- a/sddi-base/Dockerfile
+++ b/sddi-base/Dockerfile
@@ -39,13 +39,27 @@ RUN set -ex && \
     https://raw.githubusercontent.com/tum-gis/ckanext-grouphierarchy-sddi/${CKAN_EXT_SDDI_VERSION}/requirements.txt && \
   ls -lah /wheels
 
+# ckanext-hierarchy ###########################################################
+ARG CKAN_EXT_RELATION_VERSION="ckan-2.9"
+ENV CKAN_EXT_RELATION_VERSION=${CKAN_EXT_RELATION_VERSION}
+
+RUN set -ex && \
+  mkdir -p /wheels && \
+  pip wheel --wheel-dir=/wheels \
+    git+https://github.com/tum-gis/ckanext-relation-sddi.git@${CKAN_EXT_RELATION_VERSION}#egg=ckanext-relation && \
+  pip wheel --wheel-dir=/wheels -r \
+    https://raw.githubusercontent.com/tum-gis/ckanext-relation-sddi/${CKAN_EXT_RELATION_VERSION}/requirements.txt && \
+  curl -o /wheels/ckanext-relation.txt \
+    https://raw.githubusercontent.com/tum-gis/ckanext-relation-sddi/${CKAN_EXT_RELATION_VERSION}/requirements.txt && \
+  ls -lah /wheels
+
 ###############################################################################
 # Runtime stage
 ###############################################################################
 ARG CKAN_VERSION=2.9.7
 FROM ghcr.io/keitaroinc/ckan:${CKAN_VERSION} as runtime
 
-ENV CKAN__PLUGINS image_view text_view recline_view datastore datapusher envvars hierarchy_display hierarchy_form display_group
+ENV CKAN__PLUGINS image_view text_view recline_view datastore datapusher hierarchy_display hierarchy_form display_group relation envvars
 
 USER root
 
@@ -71,6 +85,11 @@ RUN set -ex && \
   pip install --no-index --find-links=/srv/app/ext_wheels ckanext-grouphierarchy && \
   pip install --no-index --find-links=/srv/app/ext_wheels -r /srv/app/ext_wheels/ckanext-grouphierarchy.txt
 
+# ckanext-hierarchy ###########################################################
+RUN set -ex && \
+  pip install --no-index --find-links=/srv/app/ext_wheels ckanext-relation && \
+  pip install --no-index --find-links=/srv/app/ext_wheels -r /srv/app/ext_wheels/ckanext-relation.txt
+
 RUN set -ex && \
   ckan config-tool "${APP_DIR}/production.ini" "ckan.plugins = ${CKAN__PLUGINS}" && \
   chown -R ckan:ckan /srv/app && \