DP Calendar Custom Search Fields

I have a Joomla site running DP Calendar and need its front-end search extended with additional custom fields. The goal is to let visitors refine results through a single/multi dropdown list that pulls from several custom fields (I will finalise the exact attributes shortly—currently marked “tba”).

Key points
• Multiple custom fields will feed the dropdown, so the solution must support list/multi-select sources.
• Only a dropdown input is required; no checkboxes or text boxes.
• The work should integrate cleanly with DP Calendar and standard Joomla practices, surviving core and extension updates.

Deliverable
A plug-in or override that adds the new dropdown filter to the DP Calendar search module/component, loads the field options dynamically, and passes the chosen value to the event query so results filter correctly.

Acceptance
I will test on a staging site: selecting any value in the new dropdown must instantly narrow calendar results to the corresponding events, with no errors in the Joomla logs.