I have created a MS Word document for mail merge. The data source is an MS Excel spreadsheet.

I want to insert a field to call a user-defined function --- this function should
accept a parameter and then returns a value (which should be displayed in the document). The parameter will be a field in the spreadsheet.

This is what I want to put in the field :-
= getSuburb (LaneNo)

laneNo = 1, the document displays "Eastwood"
laneNo = 2, the document displays "Flemington"

I could not figure out how to do this. I've tried insert field or insert formula but it didn't work. (I know how to write the function, but don't know what MS Word feature to use to call it in MS Word)

Please help.