how to restrict Hiring manager and Recruiter lov while creating a requisition

Summary:

we have a requirement to while creating a requisition Hiring Manager and Recruiter values should be excluded of one business unit. we have 3 business units in 3 countries and we would like the recruiter to see Hiring manger and Recruiter values from 2 business units of 2 countries and exclude the other country and business unit.

example: we have business units A, B and C in UK,Belgium and US respectively, we want recruiter to see business unit A, B employees in UK and Belgium to appear in Hiring manager and Recruiter LOV's excluding Business unit C in US. how to achieve this requirement. does any one has come across such requirement if so how did you come up with solution