diff --git a/scripts/5_pose_estimation.py b/scripts/5_pose_estimation.py
index 4d181aa..6c23805 100644
--- a/scripts/5_pose_estimation.py
+++ b/scripts/5_pose_estimation.py
@@ -230,11 +230,29 @@ def analyze_chain(fk: RobotFK) -> Dict[str, Any]:
         for x in pending:
             var_block[x] = len(blocks) - 1
 
+    # subtree_markers[L] = L's own markers + all descendants' markers. Lets
+    # observability() credit a block whose own link saw nothing this capture
+    # but whose CHILD link did (e.g. Ellbow has no visible markers, but Arm2's
+    # markers still constrain z through the chain — same idea as 4b's
+    # Fallback-1, just for confidence reporting here, not for the fit itself).
+    children: Dict[str, List[str]] = defaultdict(list)
+    for ln, ld in links.items():
+        p = ld.get("parent")
+        if p:
+            children[p].append(ln)
+    subtree_markers: Dict[str, List[int]] = {}
+    for ln in reversed(topo):
+        ids = list(link_markers.get(ln, []))
+        for c in children.get(ln, []):
+            ids.extend(subtree_markers.get(c, []))
+        subtree_markers[ln] = ids
+
     return {
         "ordered_vars": ordered_vars,
         "var_type": var_type,
         "var_links": dict(var_links),
         "link_markers": link_markers,
+        "subtree_markers": subtree_markers,
         "blocks": blocks,
     }
 
@@ -518,16 +536,25 @@ def observability(chain: Dict[str, Any], obs: Dict[int, Dict[str, Any]]) -> Dict
     driven by markers-per-variable in that block:
         high   : >= 2 markers per variable (well over-determined)
         medium : >= 1 marker  per variable
-        low    : fewer markers than variables (under-determined — distrust!)
-        none   : no markers at all (variable left at 0)
+        low    : fewer markers than variables (under-determined — distrust!),
+                 OR no own markers seen but a child link's markers were
+                 (indirect evidence through the chain, e.g. Ellbow via Arm2)
+        none   : no markers at all, not even indirectly (variable left at 0)
     """
     info: Dict[str, Dict[str, Any]] = {}
+    subtree_markers = chain.get("subtree_markers", {})
     for block in chain["blocks"]:
         seen = [m for m in block["markers"] if m in obs]
+        indirect = False
+        if not seen and block["anchor"]:
+            seen = [m for m in subtree_markers.get(block["anchor"], []) if m in obs]
+            indirect = bool(seen)
         nvars = max(1, len(block["vars"]))
         ratio = len(seen) / nvars
         if len(seen) == 0:
             conf = "none"
+        elif indirect:
+            conf = "low"  # indirect/coupled through a child link, not direct
         elif ratio >= 2.0:
             conf = "high"
         elif ratio >= 1.0:
@@ -537,7 +564,7 @@ def observability(chain: Dict[str, Any], obs: Dict[int, Dict[str, Any]]) -> Dict
         for v in block["vars"]:
             info[v] = {"observable": len(seen) > 0, "n_markers": len(seen),
                        "block_vars": len(block["vars"]), "confidence": conf,
-                       "block_anchor": block["anchor"]}
+                       "block_anchor": block["anchor"], "indirect": indirect}
     return info
 
 
diff --git a/scripts/__pycache__/5_pose_estimation.cpython-311.pyc b/scripts/__pycache__/5_pose_estimation.cpython-311.pyc
index 63ef7df..eaf2566 100644
Binary files a/scripts/__pycache__/5_pose_estimation.cpython-311.pyc and b/scripts/__pycache__/5_pose_estimation.cpython-311.pyc differ
diff --git a/scripts/robot_1781069752019.json b/scripts/robot_1781069752019.json
index a9d922e..fa5031d 100644
--- a/scripts/robot_1781069752019.json
+++ b/scripts/robot_1781069752019.json
@@ -288,7 +288,7 @@
         "name": "Joint1",
         "type": "revolute",
         "axis": [-1, 0, 0],
-        "origin": [110, 107.457, 37.242],
+        "origin": [110,  101.1, 55.2],
         "rotation": [0, 0, 0],
         "variable": "y"
       },