Adding an additional resource on serverless for AWS API Gateway - amazon-web-services

Question

I have a serverless app with a http event. I need to create a child resource to the endpoint created by serverless.
How can I accomplish this with serverless?
The template looks like this so far:
provider:
name: aws
runtime: nodejs8.10
region: <REGION>
functions:
myFunc:
timeout: 30
handler: "index.handler"
name: "myFunc"
events:
- http:
path: /myFunc
method: post
cors: true
resources:
Resources:
saysResource:
Type: "AWS::ApiGateway::Resource"
Properties:
RestApiId:
Ref: ApiGatewayRestApi
ParentId:
Ref: <NEED_/myFunc_RESOURCE_ID_HERE>
PathPart: "{says}"
GetMethod:
Type: "AWS::ApiGateway::Method"
Properties:
HttpMethod: GET
RequestParameters:
'method.request.path.says': true
RestApiId:
Ref: ApiGatewayRestApi
ResourceId:
Ref: saysResource
Integration:
Type: aws
Credentials:
Ref: S3ReadAccessRole
IntegrationHttpMethod: GET
PassthroughBehavior: WHEN_NO_MATCH
RequestParameters:
'integration.request.path.key': 'method.request.path.says'
Uri: 'arn:aws:s3:::my-bucket/users/{key}'
As an attempt to get it working, I re-declaration of the resource for /myFunc was performed(hoping that CFN would not create already created resources):
myFuncResource:
Type: "AWS::ApiGateway::Resource"
Properties:
RestApiId:
Ref: ApiGatewayRestApi
ParentId:
Fn::GetAtt:
- ApiGatewayRestApi
- RootResourceId
PathPart: "/myFunc"
This failed with the error:
An error occurred: myFuncResource - Another resource with the same parent
already has this name: my-func (Service: AmazonApiGateway; Status Code:
409; Error Code: ConflictException; Request ID: <Request_Id>).