I think you have two options: Use inlcudes instead of .tt's or write your generated code to SQL files from one template.
For the first approach, all you'd have to do is change the extensions on your .tt files to something like .ttinc and make sure they aren't set to auto generate. That way they only be run when included from another text template.
Then, you can include them like this:
<#@ include file="TestData.ttinclude" #>
Another option would be to write out the generated code to separate files from one master template. Oleg Sych has written about this on his blog.