M1 grids are SQL queries converted to spreadsheet (grid). This means one doesn’t need to be limited to just using the “Add Table” button. The “Tables” field is the FROM part of the query. The “Fields” popup is the SELECT part of the query. The “Filter” field is the WHERE part of the query. There is a length limit on the “Tables” field and if I remember correctly you can only nest/include one (mayyyybe two) subquery.