As far as salary basis creation is considered you can create a new salary basis in Latin America Business group which can be assigned to employees of Latin America BG.
The question which you I need more clarity for further understanding is that - Does the same employee is active in both the business group at the same time?
Because as per the current functionality which I understand an employee can have active assignment in only one BG at a particular requirement.
This is a limitation with Oracle EBS which is rectified in Fusion Apps.
A person record is always defined in a BG.
If the person is transferred to a new country(BG), then you can terminate the person in BG1 and re-hire in BG2.
But if you want to have active assignments in both BGs, then you need to have 2 person records(one in each BG)
System treats it as if they are different people.
Hope that helps.