diff --git a/wp-creation-app.js b/wp-creation-app.js
index 9726421..e5c61b7 100644
--- a/wp-creation-app.js
+++ b/wp-creation-app.js
@@ -207,12 +207,24 @@ function unitOptions(cur){
   if(c && !list.includes(c)) list.unshift(c);
   return `<option value="">Unit…</option>`+list.map(u=>`<option ${c===u?'selected':''}>${esc(u)}</option>`).join('');
 }
+// Discipline column on the BOM appears only for multi-discipline packages, so a
+// split hands each instance just its own materials. Keeps a stale value as an
+// option (mirrors unitOptions) if the discipline was later removed.
+function matDisciplineOptions(cur){
+  const list=pkgDisciplines.slice(); const c=cur||'';
+  if(c && !list.includes(c)) list.unshift(c);
+  return `<option value="">—</option>`+list.map(d=>`<option ${c===d?'selected':''}>${esc(d)}</option>`).join('');
+}
 function buildMaterials(){
+  const multi=isMultiDiscipline();
+  const th=document.getElementById('mat-disc-th'); if(th) th.style.display=multi?'':'none';
   const tb=document.getElementById('material-body'); tb.innerHTML='';
   pkgMaterials.forEach((m,i)=>{ const tr=document.createElement('tr');
+    const discCell = multi ? `<td><select onchange="pkgMaterials[${i}].discipline=this.value">${matDisciplineOptions(m.discipline)}</select></td>` : '';
     tr.innerHTML=`<td><input type="text" value="${(m.qty||'').replace(/"/g,'&quot;')}" placeholder="20" oninput="pkgMaterials[${i}].qty=this.value"></td>
       <td><select onchange="pkgMaterials[${i}].unit=this.value">${unitOptions(m.unit)}</select></td>
       <td><input type="text" value="${(m.desc||'').replace(/"/g,'&quot;')}" placeholder="3/8 lock washers gold" oninput="pkgMaterials[${i}].desc=this.value"></td>
+      ${discCell}
       <td class="center"><button class="row-del" onclick="removeMaterial(${i})">✕</button></td>`;
     tb.appendChild(tr); });
 }
@@ -305,7 +317,7 @@ function toggleDiscipline(d,on){
   pkgDisciplines.forEach(x=>{ if(!pkgScope[x]) pkgScope[x]=['']; if(!pkgDiscStatus[x]) pkgDiscStatus[x]=getRadio('status')||'Draft'; });
   Object.keys(pkgScope).forEach(x=>{ if(!pkgDisciplines.includes(x)) delete pkgScope[x]; });
   Object.keys(pkgDiscStatus).forEach(x=>{ if(!pkgDisciplines.includes(x)) delete pkgDiscStatus[x]; });
-  buildDisciplinePicker(); renderScope(); track('discipline_toggle',{count:pkgDisciplines.length});
+  buildDisciplinePicker(); renderScope(); buildMaterials(); track('discipline_toggle',{count:pkgDisciplines.length});
 }
 
 // Show the flat work-step list for 0–1 disciplines; per-discipline sections for 2+.
@@ -399,6 +411,7 @@ function splitByDiscipline(){
       scope:{[d]:steps.length?steps:['']},
       discStatus:{[d]: (pkgDiscStatus[d]||base.status||'Draft')},
       status: pkgDiscStatus[d]||base.status||'Draft',
+      materials: (base.materials||[]).filter(m=>m.discipline===d),
       workSteps: steps, work: steps.join('\n'),
       instanceOf: masterId, instanceLabel: suffix, parentNumber: baseNumber,
       split:false, children:undefined,
@@ -412,7 +425,9 @@ function splitByDiscipline(){
   editingId=masterId; saveStore(); renderSavedList();
   track('wp_split',{disciplines:pkgDisciplines.length});
   toast('Split into '+children.length+' discipline instances');
-  alert('Created '+children.length+' instances:\n\n• '+children.map(c=>c.number+'  ('+c.disciplines[0]+')').join('\n• ')+'\n\nThe master '+baseNumber+' is kept as a roll-up. Edit each instance from the Saved Work Packages list.');
+  const untagged=(base.materials||[]).filter(m=>!m.discipline).length;
+  const matNote = untagged ? `\n\nNote: ${untagged} material line${untagged===1?'':'s'} had no discipline tag and stayed on the master only — tag them before splitting to route them to an instance.` : '';
+  alert('Created '+children.length+' instances:\n\n• '+children.map(c=>c.number+'  ('+c.disciplines[0]+', '+(c.materials?c.materials.length:0)+' material line'+((c.materials&&c.materials.length===1)?'':'s')+')').join('\n• ')+'\n\nThe master '+baseNumber+' is kept as a roll-up.'+matNote);
 }
 
 // ── ASSETS (controls.dev) ────────────────────────────────────────────────────
@@ -690,8 +705,9 @@ function renderPackage(pkg){
     <tr><th>Labor Est. Hrs.</th><td>${cell(pkg.hours)}</td></tr>
     <tr><th>Package Predecessor</th><td>${pkg.seq?('After: '+esc(pkg.seq)):'None (no predecessor)'}</td></tr>
   </tbody></table>`;
-  if(pkg.materials&&pkg.materials.length){ h+=`<h2>4.0 Material List</h2><table><thead><tr><th style="width:80px">Qty</th><th style="width:80px">Unit</th><th>Description</th></tr></thead><tbody>`;
-    pkg.materials.forEach(m=>h+=`<tr><td>${cell(m.qty)}</td><td>${cell(m.unit)}</td><td>${cell(m.desc)}</td></tr>`); h+=`</tbody></table>`; }
+  if(pkg.materials&&pkg.materials.length){ const showDisc=pkg.materials.some(m=>m.discipline);
+    h+=`<h2>4.0 Material List</h2><table><thead><tr><th style="width:80px">Qty</th><th style="width:80px">Unit</th><th>Description</th>${showDisc?'<th style="width:120px">Discipline</th>':''}</tr></thead><tbody>`;
+    pkg.materials.forEach(m=>h+=`<tr><td>${cell(m.qty)}</td><td>${cell(m.unit)}</td><td>${cell(m.desc)}</td>${showDisc?`<td>${cell(m.discipline)}</td>`:''}</tr>`); h+=`</tbody></table>`; }
   if(pkg.attachments&&pkg.attachments.length){ h+=`<h2>5.0 Drawings & Attachments</h2><table><thead><tr><th>Document</th><th style="width:60px">Rev</th><th>Link / Note</th></tr></thead><tbody>`;
     pkg.attachments.forEach(a=>h+=`<tr><td>${cell(a.doc)}</td><td>${cell(a.rev)}</td><td>${a.link?linkify(a.link):ns()}</td></tr>`); h+=`</tbody></table>`; }
   h+=`<h2>6.0 Kitting & MIMO</h2><table><tbody>
diff --git a/wp-creation-index.html b/wp-creation-index.html
index 2f21596..9394494 100644
--- a/wp-creation-index.html
+++ b/wp-creation-index.html
@@ -114,7 +114,7 @@
   <div class="card">
     <div class="sub-heading">Material List</div>
     <div class="notice">Structured bill of materials. Feeds kitting and the delivery forecast. Unit is from the Acumatica unit list.</div>
-    <div class="table-wrap"><table><thead><tr><th style="width:90px">Qty</th><th style="width:120px">Unit</th><th>Description</th><th style="width:44px"></th></tr></thead><tbody id="material-body"></tbody></table></div>
+    <div class="table-wrap"><table><thead><tr><th style="width:90px">Qty</th><th style="width:120px">Unit</th><th>Description</th><th id="mat-disc-th" style="width:140px;display:none">Discipline</th><th style="width:44px"></th></tr></thead><tbody id="material-body"></tbody></table></div>
     <div class="material-actions">
       <button class="add-btn" onclick="addMaterial()">+ Add Material Line</button>
       <button class="add-btn" onclick="document.getElementById('material-import').click()">⤒ Import from Excel/CSV</button>