Migrating from Dataset to Datamart

Hi, 

I am having problems migrating our existing reports from datasets to a datamart. 

Usually when you try to split the report from the dataset you delete all tables and queries and then reconnect to the new dataset. That has worked fine so far. However, when I try to do the same but reconnect with direct query on the datamart I am facing the issue, that it generates a new dataset right behind the datamart-dataset (seen in the lineage). 

How can I avoid the extra dataset? I only want the dataset generated by the datamart.

Any tips where a pbix file has "hidden" links to the old dataset by (custom) visuals or something similar?

Thanks in advance!