You probably shouldn't allow the field to be edited/changed, except for data entry.
There are many ways to do this
I would use a new global field. Make it a dropdown and set up an OnObjectModify script trigger. Create a new value list (if needed, seems like you may have one already for Route. When the user clicks into the field and selects something from the dropdown, it performs a find for that selection.
Now if you want to be able to start at route, click something, then see the related buildings, select one, then see the related floors, select one-that's a conditional value list.
Phil (who I think is at DevCon this week), has posted some excellent examples from his Adventures in FileMaking, that will help.
Check this forum for 'Adventures in FileMaking' and you will find the downloads
I have made it a conditional value list, but it seems to still change the data. It brings up the correct answers, but when one is clicked it does not adjust the rest. For example, click route 1, runs through the script and is a conditional value list, pulls up the buildings associated with it. When I click on a building it does not update the floor and room number drop downs, so it is changing them in the main spreadsheet data. Could this be because it is only looking at one record and thinks I am editing it?
I am not using these to edit, just as a main page for people to be able to find their locations, press submit and it takes them to another layout of questions associated with that location.
I don't understand the spreadsheet reference.
You need to tie a script to each one, the second one should do a find that includes the value in the first dropdown AND the value in the second dropdown. The third will have to capture the values from 1, 2, and the 3rd dropdown.
Perfect, got it to work. Thanks for your help!