Linking Two drop down lists in excel but with conditions.

Prerequisite - DDL1 is set to a cell say D4, but DDL2 can be in multiple cells like E4...E5...E6 & so on

I have got Two drop down lists namely DDL1 & DDL2. Both the lists will share same values. I am expecting,

Condition 1:

if value in DDL1 is selected as VALUE1, DDL2 should get overridden with VALUE1.

Condition 2:

Unlike if user selects any value in DDL2 say VALUE2, neither DDL1 value should change nor other DDL2 values the value should remain as VALUE1.

Awaiting reply.

Thanks
Akshat