Is a life-partner visa to reside in South Africa possible if the South African partner is still legally married?

In the event that a South African citizen or South African permanent resident holder has a life-partner (not married), but is consequently legally married to another person while in this permanent relationship, the life-partner visa / visa cannot be applied for to reside in South Africa with this person.  A divorce decree is required to be presented to the Department of Home Affairs in order to obtain a life-partner visa.