When I make it reversible I just cut out two jumpers. I leave one side seam on the "lining" and the main print open and that's where I turn everything at. You're able to machine sew the main dress and part of the "lining" then you have to hand sew the remainder of the lining. I have trouble getting the hand stitching "perfect" so I don't make too many of them to reverse, I just "line" them.
Good Luck,
Susan

Here is one on ebay in a size 3...may be too large but you could probably adjust it fairly easily. Is this what you're looking for?

MeMo

Here is a link that might be useful: Jumper pattern

Hi Brenda, I'm making reversible jumpers/sundresses for my 1 year old DGD. I'm using Butterick pattern #3846. Just cut the lining fabric out of a companion fabric and there you go. I've also made the pants reversible, so they can change too. So much better to be able to turn something inside out when they get a stain on one side when you are out.
I like this one because there are no buttons or buttonholes! I was surprised how easy it went together and how quickly.
Kathy G in MI

Here is a link that might be useful: Butterick 3846