Hello Jeff, 

Generally, there is no need to do that, but nevertheless, you can achieve it using the following event : https://docs.telerik.com/kendo-ui/api/javascript/ui/grid/events/filtermenuopen 

Similar to this sample:
https://docs.telerik.com/kendo-ui/knowledge-base/default-grid-filter

Here is another live dojo sample to demonstrate how you can access the generated dropdowns:
https://dojo.telerik.com/IfOditAt/2

In case you are using different filter mode, the event is called columnMenuOpen:
https://docs.telerik.com/kendo-ui/api/javascript/ui/grid/events/columnmenuopen

Here is the updated sample with this logic applied:
https://dojo.telerik.com/IfOditAt/6

I hope this will prove helpful.

Regards,
Eyup
Progress Telerik