Hey Ben,
Thanks for reaching out! That looks like an awesome customization you are working on.
Though we are limited in supporting customization, I should be able to give you some tips on this one.
To the best of my knowledge there is no direct function to get the inbetween months. It should be possible with some workaround.
When you have the start and end date, then get the difference (number of days of months) and that should help you generate the new class.
If it’s a specific case (Nov – Jan), then you can do a comparison like if end month is smaller then start month and do proper adjustments like:
for ( increase month ): if month is bigger than 12 then deduct 12
Hope this helps. Let me know.
Cheers,
Andras