Major help needed! Interactivity being stripped out when merging 2 PDFs together

I’m working on a large project with two interactive documents, both created and made interactive in InDesign. They need to be combined into a single PDF for display on one iPad at a trade show.

When I try to merge them in Acrobat, I get the following message:

"Any form fields that have the same name in the merged documents are now merged into one field. If you want the values in these fields to be unique, then you need to create a PDF Portfolio instead of merging the files. To create a PDF Portfolio, choose File > Create PDF Portfolio."

The issue is that after merging, I lose the navigation interactivity we carefully built. I tried using a PDF Portfolio, but I also need to add a cover page that links to both documents so the final output feels like one seamless, interactive experience.

I’ve also tried renaming the buttons and form fields, but that hasn’t solved the issue.

Has anyone encountered this and found a workaround? Ideally, I need a single, navigable PDF that retains all interactive features and allows linking from a custom cover page.

Is there maybe a way to use code to link between the 3 pdfs in a PDF Portfolio?