sorry for the delay in response! I think it gets really tricky doing the slip stitch at the crotch. Essentially, you’re sewing one bikini together, including the side seams, leaving the crotch seam open. Then repeating with the other side. If you put them together, right side to side and sew everything together, but the crotch seam (because you have to leave an area open), I don’t think you will be able to flip it right side out when you’re done. The only way I think it’ll work is if, when you sew the two bikinis together, right side to right side, you’re only sewing them together at the waist. Then you can flip it right side out but the crotch plus the leg seams then have to be hand sewn together so it won’t be as neat as you imagine.