adding row from two tables and union two tbls to get top 4

Question

I am having two tables with same column names(studentName, fee) from the two tables I want to add one row from both the tables i.e., the row having studenName as 'KAY'(shown in the below image) and get the top 4 students who are paying the high fee.

 

How to write a SQL Query to get my required output as the image shown below.

Thanks.