Employee's who can work at multiple work locations

Content

Looking for some best practice recommendations

We have a requirement to record where an employee is working across multiple sites/locations - capturing the site name/address

• To support site reporting - how many people are working at each site/location
• For the Line Manager to be able to validate travel expense claims
• Employees to view in self-service

As we can only capture one location per department I am thinking multiple assignments might be the only way to accommodate this, but wondering if there might be an alternative that we haven't considered. 

Have other customers faced this issue and how has it been resolved?