Change a lookup-field based on another field

Hi,

Currently, I'm building a lookup-field (FieldB) and I want to show different values based on the value of another field (FieldA) on the same table.
I created a lookup-method where I added a switch-case based on the value of the other field the lookup-field depends on.

Now, let's say the other field (FieldA) can have 3 values: A, B and C.
Whenever I create a new record, the value of FieldA is always "A" as default. When I press on the lookup-field (FieldB), I can see all the values it should show when the value of FieldA is on "A".
But when I change the value of FieldA to "B" or "C", the lookup-field still only shows the values for value "A".

How can I make so the lookup always updates it's values depending on the value of another field (in this case FieldA)?

Currently, my lookup-method on the field looks like this:

public void lookup(FormControl _formControl, str _filterStr)
{
    DummyTable    dummyTable;
    FieldAValues     ABCValues;
   
   
    dummyTable = element.args().record();
   
    ABCValues = dummyTable.ABCValues;
   
    DummyTable::lookupABCValues(_formControl, ABCValues);
}

And my switch-case:

    switch(_ABCValues)
    {
        case ABCValues::A:
            sysTableLookup = SysTableLookup::newParameters(tableNum(TableA), _ctrl);
            sysTableLookup.addLookupfield(fieldNum(TableA, ItemId));
            break;
        case ABCValues::B:
            sysTableLookup = SysTableLookup::newParameters(tableNum(TableB), _ctrl);
            sysTableLookup.addLookupfield(fieldNum(TableB, ItemId));

            break;
        case ABCValues::C:
            sysTableLookup = SysTableLookup::newParameters(tableNum(TableC), _ctrl);
            sysTableLookup.addLookupfield(fieldNum(TableC, ItemId));
            break;
    }

    sysTableLookup.performFormLookup();

I appreciate any help

AnonX