I would probably go with something that didn't have any waist straps. Maybe a pouch?
If your SIL isn't very crunchy a Maya wrap might be a little "out there", also it has a learning curve which may hamper her wearing the baby.
As for me, I had a Hotsling. It was easy to figure out, and was cool looking, so it kinda fit in. I also had a Maya ring sling but I didn't figure it out till now, 4 months later. The only problem I had with the Hotslings was that I had bought the wrong size (too small), and had to sell it. I bought it when I was 7 months preggy and didn't account for all the weight that I would gain during the last 2 months.
If your SIL isn't very crunchy a Maya wrap might be a little "out there", also it has a learning curve which may hamper her wearing the baby.
As for me, I had a Hotsling. It was easy to figure out, and was cool looking, so it kinda fit in. I also had a Maya ring sling but I didn't figure it out till now, 4 months later. The only problem I had with the Hotslings was that I had bought the wrong size (too small), and had to sell it. I bought it when I was 7 months preggy and didn't account for all the weight that I would gain during the last 2 months.