adding new array nodes [ {}, {}, ... ] in json ?

[pZq]

"EndPoints": [
{
"ServerTypes": [ "All" ],
"ChannelName": "channel-1",
"SynchronousCallTimeout": 30000
}
]

I would need the node above to be created but it seems its not possible to create this.
Only way to achieve this is to change the original json to be like
"EndPoints": [
{ }
]

Then transforming like this:
{
"EndPoints[0]/ServerTypes[]`0":"All",
"EndPoints[0]/ChannelName":"channel-1",
"EndPoints[0]/SynchronousCallTimeout":"30000"
}