You can use session access
As session access only available on qliksence server not on desktop.
Try this approach if you have few salesmen
1- Concatenate all sales data with flag.
ex- Load * , 'salesman1' as Flag from salesman1\ZSQ042.xls
Load * , 'salesman2' as Flag from salesman2\ZSQ042.xls
and in expression you have to give some conditions like