ADO - Have one pipeline across many branches trigger another pipeline

I'm working on a project where we have a front end application. This application has a second entry point I've added for our login application. So I've started setting up a new pipeline for building it. Upon a successful build & push of the login-app artifact I want the login server to also trigger a build. The backend .net app for the login server will serve the built angular app from its public folder, so hence the reason to trigger the pipeline.

In each of the repos we have three branches that we deploy from: qa, uat, and prod. So when a qa build runs for the frontend, I want the qa branch of the login server to run. Same with uat -> uat and prod -> prod. Based on the information here: https://docs.microsoft.com/en-us/azure/devops/pipelines/process/pipeline-triggers?view=azure-devops#branch-considerations it doesn't sound like I can use the pipeline triggers for this. Is there another approach we could take?

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