Initial upload. Not currently functional as a mod. Includes some slightly refactored source code as well as the original mission this was debuted in zipped up as reference + example of usage.

functions/fn_materielConsume.sqf

@@ -0,0 +1,66 @@
+/*
+ *	Author: Clarky
+ *
+ *
+ *
+ *
+ */
+
+ params ["_hq", "_amount", "_player"];
+
+// Grab all Depots at the HQ
+private _baseDetails = _hq getVariable "baseDetails";
+private _depots = _baseDetails get "depots";
+if (_depots isEqualTo []) exitWith { 
+	[
+		"CLF_ShowMessage",
+		[
+			1,
+			0,
+			"No connected supply depots found."
+		],
+		_player
+	] call CBA_fnc_targetEvent;
+	// Return false;
+	false;
+};
+
+// Check current materiel available at this base
+private _currentMateriel = 0;
+{
+	_currentMateriel = _currentMateriel + (_x getVariable ["currentMateriel", 0]);
+} forEach _depots;
+
+if (_currentMateriel < _amount) exitWith {
+	[
+		"CLF_ShowMessage",
+		[
+			1,
+			0,
+			"Not enough materiel."
+		],
+		_player
+	] call CBA_fnc_targetEvent;
+	// Return false;
+	false;
+};
+
+// Loop through and subtract materiel from the depots
+// Might work on a better way to do this eventually (i.e prioritising specific depots depending on reasons)
+// By this point we have 100% checked and confirmed there is enough materiel to proceed with the requested supply consumption, so this SHOULD BE SAFE AND NOT ALLOW OVERCONSUMPTION :)
+{
+	// If the _amount is now at 0, exit the loop early
+	if (_amount <= 0) exitWith {};
+
+	// Get currently looped depot's materiel and draw down from it
+	private _depotMateriel = _x getVariable "currentMateriel";
+	private _reduceAmount = _depotMateriel min _amount;
+
+	_x setVariable ["currentMateriel", _depotMateriel - _reduceAmount, true];
+
+	// Update remaining amount to reduce
+	_amount = _amount - _reduceAmount;
+} forEach _depots;
+
+// Return true
+true;