Internal records vs QMS

check sheets don't affect the product, Where do they go? Are they included as reference or just separate from the quality documents?

Answer:

Besides the mandatory documents and records, the ISO 9001 standard also requires the documents and records that the organization identified as necessary.

I assume that that logs and check sheets are used for processes and activities monitoring so they should be incorporated in procedures describing those processes. They may not affect the product quality directly, but they can be important for monitoring and measuring process, also they can be referenced in procedure for management review as a input element.

If the logs and check sheets are used for monitoring processes and activities they should definitely be a part of quality documents.

Here are very informative articles regarding the subject:

Some Tips to make Control of Records more useful for your QMS https://advisera.com/9001academy/blog/2014/01/28/tips-make-control-records-useful-qms/
Monitoring and Measurement: The basis for evidence-based decisions https://advisera.com/9001academy/blog/2020/09/21/how-to-perform-monitoring-and-measurement-according-to-iso-9001/