SSRS Expression to add two column from two dataset in single cell in tablix

Question

We have two dataset coming from two different databases and number of column is same in both the datasets .i need to merge both dataset into one Tablix and grouped as well into same cells .

From dataset1 we have below data

Region  rate_on_bill
India --> 111
          123
          345

From dataset2 we have below data

Region     Rate_on_bill
India       001
            002

Output    
Region  Rate_on_bill
India         001
              002
              111
              123
              345

Could you please help me this requirement ,please find the layout of report

Please let me know if any information needed for requirement prospective

Best Regards, Ravi

We need to merge two dataset with same column should come into one cell and group together.