Item substitution is a part of the Supply chain management bundle-47193 with version-5.00.19.
Enabling Item Substitution
After installing the bundle, go to Transactions -> Management -> Supply chain Management
Choose the Preferences link,
Under the Features subtab, check the Item Substitution checkbox.

Note:
- Item substitution feature works only for Inventory Item, Lot and Serial Numbered Inventory Item, Assembly Item, Lot and Serial Numbered Assembly Item.
- Use of item substitution is supported only through the user interface.
- Access to the Supply Chain Preferences page is supported only for users with Administrator roles.
- The older version of the bundle does not provide the Item substitution feature.
Limitations of Item Substitution:
- The feature supports sales orders only.
- The feature does not support item substitution at the time of item selection for manufacturing or shipping.
- The feature does not support Web Store Features.
- Use of Item Substitution requires that you check the Enable Item Substitution box for both standard and custom roles.
- Substitute items are not available on Matrix Parent Items.