Sorry if I haven't understood the question right but basically:
If you are flying to airport A and it is above minima then you only need one alternate, which must be above planning minima.
If you are flying to airport A and it is below minima, you need two alternates which must be above planning minima.
If you are flying to airport A and it is above minima, and you specify airport B as your alternate and it is below planning minima, then you can either use a different alternate or add a second alternate which is above planning minima.