Hello howard57bg,
Thank you for your question on parent page assignment. I checked into your situation and tested it on my own BoldGrid installation. I am experiencing the same thing, where the pages in the ‘Parent’ drop down list are only pages that are in the active theme. Currently, the only way to get it assigned properly is to deploy the staging site, making it active. Then the correct pages appear in the drop down. I then redeployed the former active site, switching them back. This is not ideal.
I am working with the development team on the issue so they can correct it.