You can define a calculation field in the clients table that combines the company name and Person in Charge data in a single field. I'd make it a text field with this as an auto enter calculation and then specify a unique values validation on it.
And given the limits of FileMaker value lists, you may want to use a selection portal--which can have as many columns of data as you need and can be sorted into any needed order, instead of a value list.
Thank you again, and thank you for the quick response, you single handedly have given me the tools to make this database possible. This worked perfectly, the one step i got hung up on was i had to flip the switch to calculation result is TEXT. After that it worked great.
Not quite what I recommended:
I'd make it a text field with this as an auto enter calculation and then specify a unique values validation on it.
Ok sorry, can you walk me through that? I know how to make a text field, but im not sure on the other steps (auto enter calculation)
Select the field in Manage | Database | Fields and change the Field type to Text.
Double click the field or click Options to open the Field Options dialog.
Click the auto-enter tab.
Select the Calculation option.
Since this was originally a calculation field, you should see your original expression already in place and no editing needed. Click OK.
Then clear the "do not replace existing values" option.
Click the Validation tab and select the Unique Values validation.
The reason for doing this is that when you hide the first field or sort your values on the second field, duplicate values in the second field are automatically dropped out. While the company name|Person In charge combination will likely be unique in every case, there are no guarantees that two different people named "john Smith" might go to work for the same company ans thus this validation rule will catch that case if it happens.