I need to find an DropDownList with class addressControlCountry. How?
Try this
$('#myDiv').find('.addressControlCountry');
You can use
$('#divLegalAddress).children()
If divLegalAddress has more than one children you may use .eq()-function to pick the right one.
You can scope by the outer div and then select the inner dropdown element as given below
$('.addressControlCountry','#myDiv')
What you already have should work, in theory. However, you could try one of the following:
$('#myDiv').children('.addressControlCountry')
$('#myDiv > .addressControlCountry')
Please use this
$('#myDiv > .addressControlCountry')