Is It Possible to Add Multiple Data Sources When Working From One PBI Dataset?

Hi,

I have one dataset which is 4gb dataset that I want to work with.

I want to be able to refresh only one dataset, however the way I've seen this done is to click "Get Data" and choose "Power BI Datasets". This then will not allow me to add an Excel sheet if I wanted to (yes that would be a separate refresh, but that is okay as those are small files), or add tables to specific reports, rather the to the whole dataset. 

This also constrics me from adding a second dataset if needed in the future. 

The tldr of my question is basically, is there a way to create multiple reports based on one dataset, but also be able to add tables to specific reports?