Adding multiple assets through API request

I am trying to add or update a change request within SDP, but am only able to do 1 asset at a time. Can you please provide assistance with adding multiple assets in a single request? I have tried separating the items with spaces, commas, and semicolons, all with no luck.

Parameters are:
OPERATION_Name - ADD
TECHNICIAN_KEY - 927A67B8-9C7F-4180-B437-067C54B61861
FORMAT - JSON
INPUT_DATA - {"operation":{ "details":{ ......"assets":"single asset name used"......}}} - works without issue
- INPUT_DATA - {"operation":{ "details":{..... "assets":"multiple asset names used and separated with spaces, commas, and semicolons"......}}} all resulted in no assets added

Thank you in advance for your assistance

Mike