Attachment query API

For the sake of disaster recovery (not Clearbooks's but my own), I would feel more comfortable if there was the ability to query the attachment Ids of associated objects (such as Invoices) https://github.com/clearbooks/clearbooks-soap-php/blob/master/src/Clearbooks/Soap/1/0/Invoice.php

Consider that I want to store all my expenses in my own S3 bucket so I have them in one place that's under my control. The Invoice object on the API doesn't return a list of attachment IDs in the API response. My request is that it does so or that there be another API endpoint for querying a list of attachments and the Invoice / other object ids that that attachment belongs to. And that the attachment URI (which tends to point to an AWS S3 bucket) be readable for a period of time when the API returns the result set, e.g. a la query string based auth for example: https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html