If your 'simultaneously' is within the found set, like:
Find all the records with 'SMIT', in this range find all the records with 'JONE' and in this found set find all the records with 'WILS', you need to constrain or narrow the found set.
1. Perform a find so that your database contains the found set for SMIT.
2. Switch back to Find mode and make the criteria to narrow the search to JONE and choose Requests menu > Constrain Found Set.
3. Switch back to Find mode and make the criteria to narrow the search to WILS and choose Requests menu > Constrain Found Set.
There you have the constrained found set.
If your 'simultaneously' is broadening the found set, like:
Find all the records with 'SMIT', all the records with 'JONE' and all the records with 'WILS', you need to extend the found set.
It's the same as above, just replace Requests menu > Constrain Found Set, by Requests menu > Extend Found Set.