My question relates to using the undocumented REST API Call Guide in Marketing Cloud.
I can use this API call with no issues and have used it many times before but one use case I have identified which seems to be either a limitation or a misunderstanding in the way the API call can be used and what other optional parameters are available in this call.
Perhaps I can gain more insight from the community to help me identify if it's possible considering there is no evidence of documentation around this specific route.
My limitation I have identified when performing an API call on this route is being able to distinguish between which contact record to use in the event more than one of the same contact is available within the one Data Extension specified in the API route.
Does anyone know if it is possible to identify the primary key to use along with the contact key?