How can I pass a path as a variable?

[AnaLuisaFav]

appId: bank.hom
name: Fill TED Form
env:
    BASE_PATH: ../../flows/payments/subflows/
---
- runFlow: 
    file: ${BASE_PATH}enterValue.yaml
    label: "Enter value"
- runFlow: 
    file: ${BASE_PATH}chooseLegalPerson.yaml
    label: "Choose legal person"

but when I run, I get this error:

Failed to parse file: /home/ana/app-syndic-automation/tests/test_ted_legal_person.yaml
Failed to parse file: /home/ana/app-syndic-automation/tests/../flows/payments/fillTedForm.yaml
Flow file does not exist: file:///home/ana/app-syndic-automation/tests/../flows/payments/$%7BBASE_PATH%7DenterValue.yaml