Join 3 datatables using LINQ

How to Join 3 tables using LINQ and find unmatched values from it?

Similar to Unmatched records using LINQ

The chains can be extended e.g to a third table.
But in a certain Level approaching the Task differently can have Other benefits e.g Better maintenace …

As we do face more and more compairs in table combinations e.g. Dt1 with 2. 2. With 3. 1 with 3,

the Combination with Linq and for each Activity along with Filtering, gives approches with Higher maintenace flexibilty

But stoping now the General Talk. Just give some Demo Data and lets get Develop one or more solution approaches