Map Dependency Fields - How can can I limit picklist values from a multi-select Parent field?

Map Dependency Fields - How can can I limit picklist values from a multi-select Parent field?

I know the "Map Dependency Fields" feature doesn't allow a multi-select parent field. However, I need the functionality. Can I do it through a deluge function, and would it still support color coding picklists?  We need the color coding for quick scanning and readability.

Situation:  We run sports performance training facilities. We've created a custom module "Athletes" that houses info on clients and what service categories they have purchased. Since a client can purchase multiple services, the "Category" field is multi-select.

We have certain service categories offered at certain times, and I want to filter the choices available for an athlete based on what categories they are part of.  In addition, I want to filter the available time options in a subform that we use to track attendance.

Is this possible? I'd like to know whether this is doable before spending hours on it.

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