In as much as Building A Global HR System is a lofty idea for your Company-WC, one serious consideration to be made would include culture/diversity, distance, local business environment, legislations, regulatory authorities, national/local holidays etal.
What I may suggest for a start would the local harmonization of the HR functions in the 20 countries, the thinking and perception of the different workforce should be brought to the level of a globalized reasoning with the view that cross-border transfer should be enticing-then gradually a proper global mix of the Company's workforce would be attained.
It should noted that this could take a period of 3-5years of consistent working at it-then the next stage would be that the different HR heads in the 20 countries reports to a central Ombudsman at the Headquarters who has all the data supplied from the branches-with which he can now work.
Well we know of some multinationals who try to have a kind of harmonized HR -but the constraints mentioned above keeps on drawing them back-you could give your a trial ofr understudy Companies such as Shell, Mobil etal.
17th January 2005 From Nigeria, Lagos