# Relationships

Relationship endpoints enable creating, updating, and fetching relationship details.

## Create or replace a twin relationship

 - [PUT /twins/relationships](https://developers.willowinc.com/openapi/willow-api/relationships/relationshipsv2_upsertrelationship.md): Only one relationship between twin T1 and twin T2 with the same name and properties can be present -- if the given relationship already exists, the operation is idempotent.
Id of the relationship will be derived by the system and will override the value present in the request.

## Retrieve a twin relationship

 - [GET /twins/{twinId}/relationships/{relationshipId}](https://developers.willowinc.com/openapi/willow-api/relationships/relationshipsv2_getrelationship.md)

## List outgoing relationships for a twin

 - [GET /twins/{twinId}/relationships/outgoing](https://developers.willowinc.com/openapi/willow-api/relationships/relationshipsv2_getrelationships.md)

## List incoming relationships for a twin

 - [GET /twins/{twinId}/relationships/incoming](https://developers.willowinc.com/openapi/willow-api/relationships/relationshipsv2_getincomingrelationships.md)