Hello @wmyslewski and welcome to the customer community. Thanks for reaching out.
When creating the GTINs, you can use the existing UPCs as a staring point, please. For your Eaches you can add two leading zeros and keep the same check digit, while for the Cases you can update the Indicator Digit to a different digit (usually a 1) and also recalculate the check digit.
You can add the SCC codes in the Alternate Item Identification Agency field as an Assigned by Manufacturer value in case you also want to provide this information to your retailers as well.
Please let us know if this helped or if there is anything else we can do for you.
