Unfortunately I think you need to buy new sheet protectors (i.e. another brand). Not all post bound albums have the same spacing on the posts. If they are just shifted up or down a little bit, but still fit the posts I don't worry about it, but that's just me.
We have one craft store in the area that has one sheet protector from each package taped to the shelf below the product. It's very handy because you can take the scrapbook you need to match and see if they fit.