Hello @wbjkr and welcome to ACF.
I have published several examples other than the one you mention. https://github.com/Hube2/acf-dynamic-ajax-select-example. While there is nothing exactly like what you’re looking for, what you want combines what is in the select example https://github.com/Hube2/acf-dynamic-ajax-select-example/tree/master/dynamic-select-example and the relationship example https://github.com/Hube2/acf-dynamic-ajax-select-example/tree/master/dynamic-fields-on-relationship.
The only real difference from any of the examples will be in the PHP function that runs on the ajax request. In this case you’ll be getting values from the options page to return.
I don’t have time at the moment to put any code together for this.
