Automate AWS device group creation

Hello,

I'm trying to automate AWS account device group creation. The thing is I will not always have immediate access to the onboarded environment, so I wanted to reuse the external ID as it is possible in the UI (see the attached screenshot). I'm having difficulty finding the proper parameter in Python library, and the creation fails with error {"errorMessage":"No external ID assigned. Please request your external ID first","errorCode":1400,"errorDetail":null}. Is there any way to automate this?

Thanks.