Web Services Dymanic Partitioning partitions manipulation in after rule

I want to use Dynamic Partitioning in Sailpoint Web Service Connector. There is no endopoint that would return possible partitions but I want to create them in after operation rule based on some attribute value:
Get Partitions operation response is:

{
    "MESSAGE": "Success",
    "STATUS": true,
    "RESULT": [
        {
            "COMPANY": "ACME",
            "CO": "ACMELAND",
            "ACME_DEPARTMENTS": "3"
        }
    ]
}

Now based on value in ACME_DEPARTMENTS attribute I prepare list of partitions:

{
"departments": [
     "1",
     "2",
     "3"
]
}

How should I configure operations that this list is recognized as partitions to be created? Should I return it as “data” map in the after provisioning rule, add it to requestEndPoint/responseObject? I tried these things but didn’t succeed. How do I do it exactly?
@kskendelis @Paul_Meyer, I see that you discussed it in another topic: https://developer.sailpoint.com/discuss/t/webservices-parent-child-request/12935, maybe one of you could help me with that?

You really need your get partitions API call to return a list, not a count. In the absence of that, you just need to create an after operation rule that reads the response and then replaces the response entirely, with an alternate JSON message containing a list. Then you need to write the response details in the connector to interpret that new response.