I’m not sure if this is what you are looking for, but I think if it’s the same app but just different URL query parameters then then you can inspect the dcc.Link at callback time and flask.request.headers.get('Referer', '') at layout time.
Examples of URL handling examples at callback time here: https://dash.plot.ly/urls
And I have a couple of examples of doing the same but at layout time here: Example: Creating Multi-Page and Custom-Page apps at layout time