Default dropdown value based on selected record

Hi!
Trying to set the default value for

{
                            label: "Start: <font color=red><b>*</b></font> ",
                            name: "cdi_mileage.startsite",
                            type: "select",
                            placeholder:"select"
                        },

based on the value for startsite column selected from the table.

I tried .set and .val in initedit but neither worked.

The controller is set up as follows:
```
.Field(new Field("cdi_mileage.startsite")
.Options("cdi_address_book_relationships", "id", "site_aka", q => q.Where("ClinicianName", mycookie, "="))
)
``