Custom Function Needed using Google Apps Script

I have a specific problem I am trying to solve using a custom function on google sheets. I would like you to write a custom function or use current function in order to solve the problem I have.

I will try and explain this problem below: If all the matching fields within the two datasets match, i.e. city, function and age, then I would the name of the matching row to be printed in a new column of data set 2.
However, more than one row can match so that you may end up with a list of row names from dataset 1 in the new field in data set 2.

Thanks, Sam