I'm not an expert but when I was thinking about getting a Rabbit I found this link to be helpful, it was pretty much the same thing that a lady at the shelter told me .
Edit: I think your SIL is super sweet to be looking out for this Bun bun *HUGS* .
Noel- 4 year old black and white cat
Felix- 6 year old black cat
Maggie-3 year old Newfoundland Dog
Sparkie- Puppy Shih zu