Get related value automatically depends on other related filed selction

Hi,

I have 3 table as USER,Reviwer and Admin.

The relation I have created is 1 reviwer can have Multiple user and Admin can have multiple reviewer.

I want to do like this..
  When user selects Reviewer for him the related admin for particular reviewer has to get populate on User table..
I don't want do using conditional dropdown as user has to pick the name of admin in that option.

How can i do this??

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Chethana Shetty
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