Is it possible to set the RowSource for a ComboBox based on a condition?

For ComboBox1 I would like to set the RowSource as follows:

If ActiveWorkbook.Worksheets("FR Launch Sheet").Range("B3") = Sat then
Rowsource would be 'Routes'!$E$2:$E$61

If ActiveWorkbook.Worksheets("FR Launch Sheet").Range("B3") = Sun then
Rowsource would be 'Routes'!$H$2:$H$61

If ActiveWorkbook.Worksheets("FR Launch Sheet").Range("B3") did not equal
Sat or Sun then Rowsource would be 'Routes'!$B$2:$B$61