Unfortunately if you change the Supplier SKU in Retail Express, eCommerce will see this as a new product and it will NOT change or update the old product any more.

Retail Express has an option to add unlimited barcodes to an item and you should consider using this instead.  

Multiple Barcodes for the same product are used by suppliers for a variety of reasons, for example:

The same product sourced for different markets e.g. Australian vs United States

Different barcodes for different batches of products

Updated packaging

With this new update to Retail Express you'll be able to enter up to a maximum of 20 barcodes for each product, scan any of these codes, and find the same product! Multiple Barcodes are available in POS, Stock Ordering and Receiving, Stocktakes and more!

The other solution is to turn off the integration, update the two systems SKU's and then once both systems are update turn it back on re-loading both systems.

There are 2 options:

1: The simplest process is to let us know when you would like to change a supplier SKUs. You can update your eCommerce system as required however this will "break" the link. Contact us when you are ready and we will then pause the integration while you manually update Retail Express (and complete your eCommerce system.) Once you have finished you can let us know and will will check the integration link to make sure they still align, if all is ok we will start the integration again.

2: The following will also work - Update the supplier SKUs in REX to the new values, the integration would then create these new products in eCommerce. You can then move the images and descriptions over to the new product and delete the old one. The integration will now be linked to the newly created product.

Products can still remain linked between Retail Express and your eCommerce store and not be available from your store front. You can unpublish the product from your store front during these changes to ensure they are not bought in error.

Similar constraints apply when changing the Manufacturer SKU, the system will be trying to update based upon the original settings.