WebclientDataset to append using ROWS?

Hi , i have the following code which the _data come from the TWebHttpRequest response ,

i have no problem with this , 

fDataset.Rows := TJSArray(TJSJSON.parseObject(_data));

but what i wish to achieve is that , after the fDataset is opened , when the next round , i get 
the TWebhttpRequest response, i need to get the fDataset to append the "NEW" _data but keeping the existing data , at the same time i also require to check if the key is duplicated , overwrite the existing record if primary exists .

i can do this by making each of my table having a pair of TWebClientDataset , so the fDataset.row
once get the new Response , i can always load into the fDataset which is acting as temporary 
table to load the ROWS and then looping it and copy it to the table , but this will make
my data modules, full of Dataset components and my app have hundreds of table and that can easily
make my module un-maintainable , i am looking for ways to plan for my code maintenance
and try to keep it simple , can u please advice ?

and i saw the cds code has this TClientDataProxy ,not sure how to use it , will that be useful ?

Thanks.
kalmen

At this moment there isn't a built-in method. We'll check this with the RTL team.