You can refactor your forms into multiple XDP files (using fragments), but if you want to store non-XDP (LiveCycle) content in your form, you can embed SWFs and images. All other formats can only be stored in a PDF as attachments.
and you can access the attachment with scripts. e. g. you can attach your current vendor list with Acrobat. Then you can add the vendor's address via scripting even when your data source only provides the vendor number.