[Rise]

dmi, тогда так:

[{
	"Itemid":35,
	"name":"test",
	"hide":0
},{
	"Itemid":36,
	"name":"test22",
	"hide":0
},{
	"Itemid":37,
	"name":"test33",
	"hide":0,
	"childId": [39,40]
},{
	"Itemid":38,
	"name":"test32",
	"hide":0
},{
	"Itemid":39,
	"name":"test44",
	"hide":0
},{
	"Itemid":40,
	"name":"test55",
	"hide":0
}]

или так:

[{
	"Itemid":35,
	"name":"test",
	"hide":0
},{
	"Itemid":36,
	"name":"test22",
	"hide":0
},{
	"Itemid":37,
	"name":"test33",
	"hide":0
},{
	"Itemid":38,
	"name":"test32",
	"hide":0
},{
	"Itemid":39,
	"name":"test44",
	"hide":0,
	"parentId":37
},{
	"Itemid":40,
	"name":"test55",
	"hide":0,
	"parentId":37
}]

или всё вместе