Adding in new tables from same datasource

You should be able to use the Advanced Editor in Power Query to add in your tables to your original query if you are doing some joins and such between tables. However, generally when you connect to a data source and add multiple tables, each table becomes its own query, so connecting to it again and selecting different tables would end up the same as if you had selected those tables when you originally connected. I guess it depends on your use case. But, if you edit your queries and each table is its own query, then it shouldn't matter at all.