There are a couple of ways to handle this.
You can create a variable "Type" drop down field that dictates "Support" files. Then use this variable to send it to a particular workflow. If you always use a template to create these then you can assign this variable automatically.
You can also use folders to send certain files to a particular workflow by adding a file patch condition.
The important thing to remember with workflows, especially the default one that comes with ePDM is to always have a condition specified, don't leave any of them with no conditions. For example if you have two workflows with no conditions or the same condition then PDM just picks one, last saved workflow I think. If you have workflows that are transitioned from other workflows, at least add a bogus condition so nothing can select it.
My favorite is "conditions". Easy to send document automatic to another workflow based on file type, datacard information or filepath.