I don't think the 1/8" is going to work, but, as long as you press your seams to the side, you don't need to rip out the seams. Just resew them to the 1/4". I don't pay attention to the "scant 1/4" thing, as others have said. I like Meadow Mist's comment: If they want us to use a scant 1/4" make a scant 1/4" foot! There is always going to be enough give in fabric to make up for the one or two thread width difference when nesting seams to piece.