When you are setting the properties of a file exporter, setting the Type property to Excel Spreadsheet (Multi Input) adds an extra field, Excel Template (Expr) to the property tab; see File Exporter.
Use this option to add an expression that resolves to the name of a template file, which must exist. PhixFlow uses a template file to guide which values from which input pipes are written to which cells or cell ranges in the template file.
The Excel Template (Expr) is re-evaluated inside the input multiplier loop. This means it is possible for successive evaluations of the expression to give different values. Each value represents the name of a template file, which must exist.
Each pass of the input multiplier loop generates a new output file.
