Hi @stadi ,
To replace the Excel data source by SharePoint list, first to create the SharePoint lists with the same data construct as the Excel Tables(Leave, Holidays and Balance). Make sure the column types, column names, table names consistent.
When all lists are created, First Delete OneDrive for business connections for three Tables, and then add SharePoint connection to connect to three lists with the same name as Excel tables. Then all formulas are automatically adapted to the newly added lists.
To your second requirement, it can be implemented by Approval Flow. Create an Approval Flow and apply it in the OnVisible property of ConfirmationScreen.
In Approval Flow, you need to achieve the same logic in corresponding condition as the code configured in Approve and Decline button as follows, to modify the balance based on the leave type and change the Leave statue.
Hope this helps.
Sik
