diff --git a/rsconcept/frontend/src/features/rsform/models/graph-api.ts b/rsconcept/frontend/src/features/rsform/models/graph-api.ts
index 5c1697d1..683a1902 100644
--- a/rsconcept/frontend/src/features/rsform/models/graph-api.ts
+++ b/rsconcept/frontend/src/features/rsform/models/graph-api.ts
@@ -57,11 +57,11 @@ export function applyLayout(nodes: Node<TGNodeState>[], edges: Edge[], subLabels
   });
 }
 
-export function inferEdgeType(schema: IRSForm, source: number, target: number): GraphType | null {
+export function inferEdgeType(schema: IRSForm, source: number, target: number): GraphType {
   const isDefinition = schema.graph.hasEdge(source, target);
   const isAttribution = schema.attribution_graph.hasEdge(source, target);
   if (!isDefinition && !isAttribution) {
-    return null;
+    return 'definition';
   } else if (isDefinition && isAttribution) {
     return 'full';
   } else if (isDefinition) {
diff --git a/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-term-graph/tg-flow.tsx b/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-term-graph/tg-flow.tsx
index badc2397..c1375a7b 100644
--- a/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-term-graph/tg-flow.tsx
+++ b/rsconcept/frontend/src/features/rsform/pages/rsform-page/editor-term-graph/tg-flow.tsx
@@ -88,7 +88,7 @@ export function TGFlow() {
     filteredGraph.nodes.forEach(source => {
       source.outputs.forEach(target => {
         const edgeType = inferEdgeType(schema, source.id, target);
-        if (edgeType && newNodes.find(node => node.id === String(target))) {
+        if (newNodes.find(node => node.id === String(target))) {
           const color = filter.graphType === 'full' ? colorGraphEdge(edgeType) : colorGraphEdge(filter.graphType);
           newEdges.push({
             id: String(edgeID),