Once you select the 2 companies, you have to right click on the list box and use "Select Excluded" to exclude the 2 companies alone. This would select all the other companies for analysis.
You can also,
1. Create a button
2. Go to the Actions,
3. Use Select in field
4. in the search string, you have to pass both the Companies like below
(MES Indonesia Utamam PT | CITRA Gemlang)
5. Also to dynamically pass the first 2 Companies you could use like this,
Concat(Rank(Aggr(Sum(Sales), CompanyDimension)) <=2, '|').