If I wasn't clear before, the issue is the same identical Header, Footer and Nav Bar are appearing in the iFrame child object of the parent page. Please see the attached image for details of the problem:That's because that header and footer is included in the Angular 7 application - the iframe in this context is irrelevant.
But I cannot determine exactly where this 'setting' is taking place -- either in the A1.X sub-section of the application or in the A7 sub-section.In the Angular 7 - Angular and AngularJS are completely different frameworks.
When you say master / header footer can you elaborate/
Your Angular 7 "component" will be its own stand alone system on its own URL - which implies anything rendered in the iframe is coming from the the Angular 7 side - so I am not clear on your question regarding the Master / Header issue.
If you can give me a bit more information about how the various apps are structured it?
Is your Angular 7 implementation an application or an Angular Element?