Sub-Domain Move to Backlight

I have a sub-domain site that was built about 10 years ago using various Turning Gate templates via Lightroom prior to Backlight. Is there an easy was to move these from the sub-domain to the main domain and convert them to Backlight? I have searched the documentation, but I don’t seem to find my exact answer.

Something that old won’t be convertible to Backlight. It would need to be CE4 or newer to migrate to Backlight

Thanks, that’s what I figured.