Resource Owner Password Flow
Used in: Consuming application to Resource API (End user to application)
Flow Type: Two Legged OAuth

Resource Owner Password Flow (Third Party Token Endpoint Behind )
Used in: Consuming application to Resource API (End user to application).
Flow Type: Two Legged OAuth
Protecting third party OAuth2.0 token endpoint behind API Management. Sample reference for demonstration. You need to consult your security team, if above proposal fits your security requirements accurately.