checkbox inside dropdownlist passing parameter to another dropdown

Hello Everyone,

I have two dropdown list..i wanted to have a checkboxlist inside of it that will select and uncheck all and every time I select one data it will pass the parameter automaticaly into the second dropdownlist with checkbox also..example:


Region 1 has a relation with plant1 value

1st dropdown
Region:

Region1 - selected
Region2
Region3

second dropdown
Plant:
Plant1 - selected
Plant1 - selected
Plant2
plant2
plant3
plant3

Please Anyone help me!! Thanks a Lot!!!