The article, Create deep links to content created using InDesign & in5, describes multiple approaches for creating deep links. Which approach you use is based on different scenarios such as where the content is hosted, if it's embedded, or if there are more than 1 iframe on the page.
It appears that you have presented some different scenarios. You would need to use the approach that goes with its corresponding scenario.
In the most recent scenario that you presented, you would need to use the following approach from the article:
To be able to share a link that would open the website but also load a specific page in the iframe as the first page, add the following code to the JavaScript portion of the Resources section of the Export HTML5 with in5 dialog:
function getHashPage(){
var q=(location.hash || parent.location.hash).substr(1),px=q.indexOf('p=');
return px>-1?parseInt(q.substr(px+2))||-1:-1;
}
With this function, adding the hash parameter to the top URL will load page 3 of the document in the iframe.
https://example.com#p=3
(The above script and URL work when there is only one iframe on the page.)
If you're having trouble creating deep links, then I would recommend working with a web developer.