TWebClientConnection

TWebClientConnection has property DataNode
As I understand this Node used To Load data to a TWebDataSource.

Is there way to load values to multiple TWebDataSources from one TWebClientConnection.
E.g. I want to use one http Call to fill multiple Data Sources.

You want to have these filled with the same data?
If so, any specific reason for duplicating the data in different datasets?

No.

I want to call web service that returns 2 dataset.
for example master and detail. Potentially there could be even more dataset at once.
This will amount of reduce calls to server.

So with one call I will be able to fill multiple datasets with there own data by one call to Web service.

TWebClientConnection is not the way to solve this particular need.
You'll need to perform the HTTP request to get the two datasets with one request yourself, split the returned data, parse it into 2 JSON arrays and assign these to
WebClientDataSet.Rows: TJSArray