Timeout When Accessing Settings

Does the child site have many posts/pages? If so, how many approx?

The ultimate workaround is:
install plugin tweak option, and add the required option.
example: if you want to use PSO on the album cover image, add option
wppa_coverimg_overrule with value yes

If you want a different, pls ask me

The child site has 6 pages and 2 posts.

Seeking to use the photo specific URL for a photo within a slide show.

Thank you for the prompt reply Jacob.

Here is tweak option: https://www.ads-software.com/plugins/tweak-option/

Install it and find it in the wp tools menu.
Open it and add new option:
wppa_slideshow_overrule
and give it the value yes

PERFECT, thank you Jacob!!