MasterSelectWidget with nested Slave Fields

I it possible to add a Slave Field to a Slave Field? What i mean is:

Masterfield: has three Options in a List.
If i select the Option 3 it should be displayed the Slave List with many Options. One of these Entries is labeled "Others" and it should be show a TextLine Widget for Input. Has anyone a Solution for this Situation?

What about just adding another field and hide / show the text field if 'other' is chosen?

var i= $('#id_of_field1').val();
if(i=="other") // equal to selected option

(you will have to hide the field in the schema, maybe:

I suggest to avoid staff like MasterSelectWidget and move your all logic into some dedicated jQuery code..then you have full control over the behavior instead of depending on stuff like MSW.