Hi, is it possible to set the parent & child categories selection in different drop down list??

Hi, is it possible to make the parent and child term in separate dropdown select list??
for example I have terms as below:

ParentA
-ChildAA
-ChildBA
-ChildBB
-ChildAB
-ChildAC
ParentB
-ChildBA
-ChildBB
-ChildBC

so I would want to have my 1st dropdown list only show ParentA and ParentB, and once the parent is selected, the 2nd dropdown list will have the child values for user to select depend on which parent is selected by 1st dripdown list.

Is it possilbe to do this by set the dropdown lists with same parent and with different start depth and end depth of the term?
for example:
if I set root as parent term for 1st dropdown list and with start depth 1 end depth 1, then this list will only show parents
then I'll also set root as parent term for 2nd dropdown list, but the start depth sets to 2 and end depth 3, then this list will shows the childs depend on the parent dropdown list.

maybe it's good to have an option to let user choice to links different menu together for this idea.

I think this will be very useful for users.

Thanks :)