I was able to create a very basic system that sounds like it does more or less what you want. I have a parent workflow that's splitting a multipage document into individual pages, then I'm sending EntryIDs for each single-page document via InvokeWorkflow to a child workflow that finds the single-page document, runs a capture profiles then does stuff with it (in this case, return the extracted value as an output parameter). Apologies if I'm missing the point entirely, but in any case, could you provide more details about how your workflows are configured?

Workflow to split multipage document 

The invoked workflow:

After running the parent workflow, the ExtractedValues multivalue token has a distinct value extracted from each of the pages of the original multipage pdf.