E1 Orchestration - How to create nested multi node JSON

I have a requirement to create JSON payload with multi-level/nested segments as follows. I was able to get Header and Detail nodes with two headless-detail forms but limited to two levels only. Please suggest if/how it is possible to generate such structure.

{
"Transaction": {
"Header": {
"TransactionID": "ProcOrder",
"TransactionRefID": "1CA9A176ECFB",
"SourceSiteID": "Denver",
"SourceSystem": "JDE"
},
"Detail": {
"Plant": "Aurora",
"Order": 101401,
"Product": 2323,
"RecipeID": "",
"BatchQuantity": 2700,
"BatchUOM": "EA",
"Items": [
{
"LineNo": 10,
"Item": 303,
"TotQuantity": 1.2,
"UOM": "KG",
"Allocation": {
"Lot": 20161000,
"Quantity": 1.2
}
},
{
"LineNo": 20,
"Item": 304,
"TotQuantity": 4.8,
"UOM": "KG",
"Allocation": [
{
"Lot": 20161000,
"Quantity": 4
},
{
"Lot": 201610012,
"Quantity": 0.8
}
]
}
]
}
}
}