Filter relations conditionally based on another shared relation field

Example:
I am filling a form with fields:
- group [relation]
- item_within_group [relation] (also has a relation to group)

I would like to be able to set a filter on the item_within_group field:

item_within_group.group contains selected value of field group

Example Form State - Show all options:

• Select your groups: <empty>

• Select your items: <empty>

  • Listed options:

    • “item1_group1”

    • “item2_group1”

    • “item1_group2”

    • “item1_group3”

Example Form State - Filter options based on the selection of the shared relation:

• Select your groups: "group1”, “group2”

• Select your items: <empty>

  • Listed options:

    • item1_group1

    • item2_group1

    • item1_group2