In last Mendix release *:* relations are now supported in Mendix Odata pubish.
But I am stuck how to get this working in Excel... I load succesfully the two tables in excel but I can get the relationship working... Any clues?
My experience is that 1-* in excel is a challenge is as well, while using Power BI, R or alike is a better way to go to consume and match data.
Are you using the excel exporter module? It should be able to display the data in one sheet.