How to mapping when custom target system only have Persons and Groups table

Dears,

I need to synchronization one custom target system, the target system has two table, one is Person and the other is Group.

The structure as bellow

Table: Person , Column: Userid, Name, Role_id 

Table: Group, Column: Role_id, Role_name, Role_desc

as above describe, the Role_id in Person table, if I map UNSAccountB to Person,

can it be triggered when I Assign group to person, what I mean is, the Assign event on UNSAccountBinUNSGroupB, can it trigger Modify event on UNSAccountB then provisioning to custom target system.

or other smart way?

Please advice and kindly help, very thanks~~

David