Reference shared .hcl files in multiple build files?

Is it possible for different build files to reference a shared hcl file as a module within the build{} steps?

Hello,

If I understood right what you want, I would say yes.
For example, if you have 3 files - 2 with build blocks and 1 with a source block - if the 3 files are in the same directory, you could use the source within both builds and just run packer build . to reference the whole directory.
Is that what you need?