K2 Filter : Filtering by more than one date

Hello,

I have a really specific question :

I made a php script getting all the next departure dates for our incomming travels (we are a travel agency) from our ERP and updating joomla k2 database with an texfield extrafield like this :
"October 2021;January 2022; May 2022"

But here comes the problems

I'd like to filter the search by upcomming dates but the main problem is that i may have more than one date for each item.

I'd like a dropdown selection with like 24 choices for each month on the 2 upcomming years

For now the only idea i have is to get the date extrafield from the extra_field table as a multi select list and resetting the options each month with 24 new values with a CRON on mySQL.

Then retrieving the dates in an array from our ERP like im doing at the moment and activating (or not) each select option for each item if it matches a date in the array.

This will takes a lot of time for me to make and i was wondering if you maybe had an idea on how to achieve this any other way ?