It will be the same. You might add the word "even" to emphasis that the first set was small to begin with. For example, if children are comparing how many strawberries they have on their plates... I only have a few strawberries. But you have even fewer. And John has the fewest. If the difference is small, you can use the word few to show this: "I have a few less than she has."

Interesting. I LOVE questions that teach me something about my own language. My wife and I have the same reaction: The answer is a flat "No," but we can't explain it. The expression "A few" is simply not an adjective at all. Therefore, it doesn't have comparative forms. It isn't a combination of the meanings "A" and "few," it's just one thing... "Afew" or "A-few" but with a space instead of a hyphen! Sometimes I wonder whether we should think of English, not as having "auxiliary words," but as having inflected forms that are customarily written as separate words! And now I wonder: how does "Very few" fit into this complicated picture? "A few of us speak Spanish, but very few of us speak it well, and even fewer are native speakers. Fewer than three of us studied in college."

Dan Smith makes a good point. "A few" is not really a gradable adjective, it's more of an approximate number, like "a couple of" or "a half dozen." There's no way to compare "one few" to "another few." "A few" has no degrees and no opposite, but "few" does, the opposite is "many." "Few," without "a" is gradable, and can be used with very: "very few people." Note that in spoken English, the words "fewer" and "fewest" tend to be replace by "less" and "least." This is not considered "proper diction," but you should be prepared to hear it a lot.

Thank you so much, both of you ^^! I'm clear now