How to set up multiple companies for a single partner?
Say I have three companies; CompanyA ,CompanyB and CompanyC. CompanyA and CompanyB both deal with the same customer; CustomerX.
How can I set up CustomerX so that I can invoice him from CompanyA and CompanyB but NOT let him be seen by CompanyC? (That is, I can't just leave the company field blank or CompanyC will be able to see him).