A workflow that hides fields on the customer record whenever the customer has specific subsidiary can be defined as follows:
Workflow Name: Customer Hide Details in View
Record Type = Customer
Subtype = Customer
Initiation: Event Based
Event Definition:
On Create, On Update selected
Trigger Type = Before Record Load
Event Type = View
Condition: Subsidiary = ABC Subsidiary
State 1: Hide Fields
Action 1: Set Field Display Type
Trigger On = Before Record Load
Field: Date of Birth
Display Type = Hidden
Action 2: Set Field Display Type
Trigger On = Before Record Load
Field: Language
Display Type = Hidden
Actions will have to be set for each of the fields that should be hidden on the form.