c# - pause method until button is clicked

[redivider]

I have a series of combo boxes (on a windows form) that allow the user to enter new values. A user clicks on [Other] then a text box appears letting them enter the new value.
An OK button then takes the input and adds it to the options list for that combobox. My issue is that once I transfer control to the "newValue" textbox and OK button I lose which combobox requested a new entry.
I could put the calling Control's name into an invisible control, but that hardly seems like best programming practices.
Any ideas?