You want to do this on the post-validate of each of the address columns?  If so, then you could just attach this one script to each of those post-validate events.

Yes, after a sales order imports I would like to check those fields and then SetValues.

This script is giving me the same trouble I am having with some other Header scripts.  The script fires off and works if I am manually editing the fields the script is triggered off of, however these scripts are for orders that are being imported in through Insynch.  Is there something I can add to the scripts to get them to fire off?  I have it on a column-post-validate and also tried a table-pre-totals.

rVal = 0
nCustomerNo= ""
sAddress = ""
searchString = "Terminal"

rVal = oBusObj.GetValue("CustomerNo$", nCustomerNo)
rVal = oBusObj.GetValue("ShipToAddress1$", sAddress)

If nCustomerNo = "0002000" then

	If InStr(UCase(sAddress), UCase(searchString)) > 0 then
		rVal = oBusObj.SetValue("ShipToCode$", "GM")
		rVal = oBusObj.SetValue("ShipVia$", "SHIPHOLD")
	End If		
End If

Have you tried to put them in the pre-write event?   Do you know if the scripts are even executing?  I am not familiar with InSynch's logic.  If they are using BOI, do you know if they turn off any scripting methods?  

First thing I would do is see if the scripts are executing at all.  Then if the scripts are executing, you could try the pre-write event.

ROI changed the logic of the import to write the UDF's before the line details, as of now it looks like it solved my issue.