How to add an existing campaign as a source in AdMob?

Question

Android

Hello, I can’t find the option to add an existing campaign to the sources.
For example - I have an already working banner and the default AdMob source, I want to add a home campaign as a source, but not create a new one, but select an existing one, how?
In other words - There are ready-made campaigns and ads in the "Promotion" section, they are all "house campaign", I want them to be shown in my applications, I go to "Sources" (Mediation -> * ad source), there is " Add a new home campaign "(New house ad campaign) - but there is no way to select an existing campaign, I also looked in the campaign settings and ads - there is also no way to choose where to show or I did not find