diff --git a/src/commands/index.js b/src/commands/index.js
index 4199a04..c94a6ec 100644
--- a/src/commands/index.js
+++ b/src/commands/index.js
@@ -12,42 +12,52 @@ module.exports = [
     topic: 'set.mode',
     aliases: ['setMode'],
     payloadSchema: { type: 'string' },
+    description: 'Switch the valve group between auto / manual control modes.',
     handler: handlers.setMode,
   },
   {
     topic: 'set.position',
     aliases: ['setpoint'],
     payloadSchema: { type: 'any' },
+    // Control-percent setpoint — no `units` (no `percent` measure in convert).
+    description: 'Set the group-level valve position (currently a no-op pending Phase 7).',
     handler: handlers.setPosition,
   },
   {
     topic: 'child.register',
     aliases: ['registerChild'],
     payloadSchema: { type: 'string' },
+    description: 'Register a child valve with this group.',
     handler: handlers.registerChild,
   },
   {
     topic: 'cmd.execSequence',
     aliases: ['execSequence'],
     payloadSchema: { type: 'object' },
+    description: 'Run a group-wide sequence (startup / shutdown / emergencystop).',
     handler: handlers.execSequence,
   },
   {
     topic: 'data.totalFlow',
     aliases: ['totalFlowChange'],
     payloadSchema: { type: 'any' },
+    // Compound payload `{source, action, ...}` in some shapes — no scalar
+    // normalisation. The handler routes by payload.source.
+    description: 'Notify the group that the total flow setpoint has changed.',
     handler: handlers.totalFlowChange,
   },
   {
     topic: 'cmd.emergencyStop',
     aliases: ['emergencyStop', 'emergencystop'],
     payloadSchema: { type: 'any' },
+    description: 'Trigger an emergency stop across all valves in the group.',
     handler: handlers.emergencyStop,
   },
   {
     topic: 'set.reconcileInterval',
     aliases: ['setReconcileInterval'],
     payloadSchema: { type: 'any' },
+    description: 'Update the reconciliation interval (seconds).',
     handler: handlers.setReconcileInterval,
   },
 ];
diff --git a/src/specificClass.js b/src/specificClass.js
index 4fc4432..6e470c6 100644
--- a/src/specificClass.js
+++ b/src/specificClass.js
@@ -10,7 +10,9 @@ const flowDist = require('./groupOps/flowDistribution');
 const sources = require('./sources/fluidContract');
 const io = require('./io/output');
 
-const KNOWN_POSITIONS = new Set(['upstream', 'downstream', 'atEquipment']);
+// Source softwareTypes after BaseDomain canonicalisation
+// (rotatingmachine→machine, machinegroupcontrol→machinegroup).
+const SOURCE_SOFTWARE_TYPES = ['machine', 'machinegroup', 'pumpingstation', 'valvegroupcontrol'];
 
 class ValveGroupControl extends BaseDomain {
   static name = 'valveGroupControl';
@@ -42,22 +44,10 @@ class ValveGroupControl extends BaseDomain {
     this.state = new state({}, this.logger);
     this.state.stateManager.currentState = 'operational';
 
-    // Overloaded API: `(child, softwareTypeOrPosition)`. Tests + legacy
-    // childRegistrationUtils both invoke this with a string second arg,
-    // which may be either a known position or a softwareType. Resolve
-    // before dispatching so router-based registration keeps working.
-    this.registerChild = (child, positionOrType) => this._registerChild(child, positionOrType);
-  }
-
-  _resolveRegistrationContext(child, arg) {
-    const fromArg = String(arg || '').trim();
-    if (KNOWN_POSITIONS.has(fromArg)) {
-      return { positionVsParent: fromArg, softwareType: child?.config?.functionality?.softwareType || null };
+    this.router.onRegister('valve', (child) => this._registerValve(child));
+    for (const swType of SOURCE_SOFTWARE_TYPES) {
+      this.router.onRegister(swType, (child, canonicalKey) => this._registerSource(child, canonicalKey));
     }
-    return {
-      positionVsParent: child?.positionVsParent || 'atEquipment',
-      softwareType: fromArg || child?.config?.functionality?.softwareType || null,
-    };
   }
 
   _isValveLike(child) {
@@ -69,22 +59,7 @@ class ValveGroupControl extends BaseDomain {
     );
   }
 
-  _registerChild(child, positionOrType) {
-    const ctx = this._resolveRegistrationContext(child, positionOrType);
-    const softwareType = String(ctx.softwareType || child?.config?.functionality?.softwareType || '').trim().toLowerCase();
-
-    if (softwareType === 'valve' || (!softwareType && this._isValveLike(child))) {
-      return this._registerValve(child, ctx.positionVsParent);
-    }
-    if (sources.isSourceLike(child, softwareType)) {
-      return sources.registerSource(this, child, ctx.positionVsParent, softwareType);
-    }
-
-    this.logger.warn(`registerChild skipped: unsupported child type '${softwareType || 'unknown'}'`);
-    return false;
-  }
-
-  _registerValve(child, positionVsParent) {
+  _registerValve(child) {
     if (!this._isValveLike(child)) {
       this.logger.warn('registerChild skipped: child is not valve-like');
       return false;
@@ -94,6 +69,9 @@ class ValveGroupControl extends BaseDomain {
       this.logger.debug(`registerChild skipped: valve ${id} already registered`);
       return true;
     }
+    const positionVsParent = child.positionVsParent
+      || child.config?.functionality?.positionVsParent
+      || 'atEquipment';
     child.positionVsParent = positionVsParent;
     this.valves[id] = child;
     this._bindValveEvents(id, child);
@@ -104,6 +82,13 @@ class ValveGroupControl extends BaseDomain {
     return true;
   }
 
+  _registerSource(child, softwareType) {
+    const positionVsParent = child.positionVsParent
+      || child.config?.functionality?.positionVsParent
+      || 'atEquipment';
+    return sources.registerSource(this, child, positionVsParent, softwareType);
+  }
+
   _bindValveEvents(valveId, valve) {
     const handlers = {
       onPositionChange: () => { this.logger.debug(`Valve ${valveId} position changed, recalculating flows.`); this.calcValveFlows(); },
diff --git a/test/integration/flow-distribution.integration.test.js b/test/integration/flow-distribution.integration.test.js
index f203c55..49eed23 100644
--- a/test/integration/flow-distribution.integration.test.js
+++ b/test/integration/flow-distribution.integration.test.js
@@ -84,10 +84,43 @@ test('valveGroupControl distributes total flow according to supplier-curve Kv an
   valve2.destroy();
 });
 
-test('valveGroupControl rejects non-valve-like child payload', () => {
+test('valveGroupControl skips a non-valve-like payload registered as a valve', () => {
   const group = buildGroup();
-  const result = group.registerChild({ config: { functionality: { softwareType: 'valve' } } }, 'atEquipment');
-  assert.equal(result, false);
+  // Router dispatches by softwareType; the _registerValve handler rejects
+  // non-valve-like children (missing updateFlow/state/measurements) by
+  // returning false from its branch — the registry side-effect (valves[])
+  // stays empty even though BaseDomain's registerChild returns true.
+  group.registerChild({ config: { functionality: { softwareType: 'valve' } } }, 'valve');
   assert.equal(Object.keys(group.valves).length, 0);
   group.destroy();
 });
+
+test('valveGroupControl router dispatches valve registration by softwareType, honouring config positionVsParent', async () => {
+  const valve = (function buildValveAtUpstream() {
+    const Valve = require('../../../valve/src/specificClass');
+    return new Valve(
+      {
+        general: { name: 'valve-upstream', logging: { enabled: false, logLevel: 'error' } },
+        asset: { supplier: 'binder', category: 'valve', type: 'control', model: 'ECDV', unit: 'm3/h' },
+        functionality: { positionVsParent: 'upstream', softwareType: 'valve' },
+      },
+      {
+        general: { logging: { enabled: false, logLevel: 'error' } },
+        movement: { speed: 1 },
+        time: { starting: 0, warmingup: 0, stopping: 0, coolingdown: 0 },
+      }
+    );
+  })();
+  primeValve(valve, 50);
+  const group = buildGroup();
+
+  // childRegistrationUtils consumes positionVsParent (2nd arg) and forwards
+  // softwareType='valve' to the parent — the router fans out from there.
+  assert.equal(await group.childRegistrationUtils.registerChild(valve, 'upstream'), true);
+  assert.equal(Object.keys(group.valves).length, 1);
+  const registered = Object.values(group.valves)[0];
+  assert.equal(registered.positionVsParent, 'upstream');
+
+  group.destroy();
+  valve.destroy();
+});