Any help from someone familiar with Missouri withholding is appreciated.

We're having fits getting people's net pay to agree with last year, taking over for another payroll service. The old payroll service claimed to have expertise in all states.

1. Line 1 of the Missouri W-4: When someone claims "1" does this mean they are claiming one ADDITIONAL exemption or does it mean only themselves?
2. Single vs. Married. From what I can read, if a spouse works, the effective withholding status is exactly the same as single for all calculations. This appears to be true regardless of which line is filled out. Is this correct?

Thank you for your help.