Yes, one. Yes, it can be done.
Now I will preface by saying we only have one kid. We also did this when Little V was 18 months old. I didn’t have to bring a breast pump, and we didn’t have to worry about bottles, so I personally found it easier to pack for an almost-toddler than a little baby. Time will tell whether we can pull this off again when V gets older, but hopefully she’ll be able to carry a little backpack of her own next year!