Excel Connect to Data (PBI DataSet), create measures locally???

i am in Excel with the Power BI addon, i connected to my dataset living in Power BI service online, and I can see the tables in pivot table, but 'no measures defined' error appears...  i want to create measures locally (use Power Pivot to create a model, add measures, etc) is this possible at all? any workaround to getting the original tables/data model into Excel Power Pivot ( i assume this would be the only way)

i do see you can create in Power BI desktop and publish again, but wanted to check