Function module in Infotyp which checks if identical data already exists

Question

I want to create a new hr master data (tcode pa30) for Hans Müller in e.g Company X and fill out the necessary fields in Infotype 0001,0002 (Name, Birthdate, etc. ) u2013 done !
After  creating the new hr master data for Hans Müller Iu2019d like to fill out a special Infotyp (0032) namely Internal Data.
PROBLEM:
While filling out the IT 0032 I do not know if the person - Iu2019ve created a new master data for - is already existing in the system ( but in other e.g Company Z) .
So what I need is a function modul in the Infotype 0032 which checks if there is already a person with the same data existing in any company (the whole data bank) using 3 characters from Infotype 0002 (Personal Data) namely ,   First name, Last name, Birthd. . 
And if a person with the same first name ,last name and birthday is already existing the function module should link to that one or just show me a information.
Also tried to show you my problem on a graphic,
Function_Module_Infotyp0032.png
I hope you can help me. I would be very thankful for any hints , information or programming approach.
Regards
Sean

Answer 1

the problem with your solution approach is that there could be different pers. no. for the same person in my issue.
If I understood you well, that won't be a problem, since you already know which PERNR to use (The one you are using to update IT0032) In that case you only have to check if for that PERNR more than one record in PA0001 with different Company Code is present.
If your problem is that another person with the same name and same date of birth is active in the system with different Company Codes it would be similar.
For instance: Let's say that you find 2 different PERNRs for a given Name and Date of Birth in PA0002, then you can check IT0001 and look for the BUKRS value for those 2 Personel Numbers. If the values found are different you can raise the error message or whatever you need.