Appsync js pipeline resolver functions

### Amplify CLI Version

14.0.0

### Question

I have written a custom mutation in my schema.graphql

I couldn't find a way to write a series of appsync js pipeline functions for this mutation on my local computer so I used the Appsync console to generate the appsync js functions and added them to the custom mutation's pipeline.

Sometimes, when I run amplify push, the pipeline I built via the console is preserved.
Other times, it is removed and replaced with the req and res vtl resolver that amplify generates.

1. What causes the console pipeline to be overridden on certain pushes?
2. Is there a simple way to define the pipeline on my local computer so that it can be guaranteed to persist after amplify push?