Anyone have experience with rent-controlled tenants in SF?

[Kusum Chanrai]

Hi friends! 

My husband and I are thinking about buying a MF triplex in SF in the mission district. The issue is that we have 2 rent-controlled tenants in the building. 

1) One tenant is over 60 and has lived in the unit for more than 10 years. 

2) Tenant 2 claims to be catastrophically ill and has lived in the unit for > 5 years. 

We haven't made an offer yet, and want to get an understanding of how easy/difficult it will be to legally get these tenants out (e.g. buying them out). 

Does anyone have experience with issues like this? Or know where we can learn more about options and tactics? 

Thanks all! 

Kusum.