In the PSC bulk data export the data attribute does not contain all the PSC entities. Please see the example below. On the web site this company has three PSC individuals but the export only contains the oldest.
{
"company_number": "09145694",
"data": {
"address": {
"address_line_1": "St. Andrews Road",
"country": "England",
"locality": "Henley-On-Thames",
"postal_code": "RG9 1HP",
"premises": "2"
},
"ceased_on": "2018-05-14",
"country_of_residence": "England",
"date_of_birth": {
"month": 2,
"year": 1977
},
"etag": "3b8caf795c03af63921e381f7bb8300a51ebb73d",
"kind": "individual-person-with-significant-control",
"links": {
"self": "/company/09145694/persons-with-significant-control/individual/bIhuKnMFctSnjrDjUG8n3NgOrlU"
},
"name": "Mrs Nga Thanh Wildman",
"name_elements": {
"forename": "Nga",
"middle_name": "Thanh",
"surname": "Wildman",
"title": "Mrs"
},
"nationality": "Vietnamese",
"natures_of_control": [
"ownership-of-shares-50-to-75-percent"
],
"notified_on": "2016-04-06"
}
}