I agree with Lily but also hear what you're saying about wanting her to make an informed choice Fiona. I think, rather than trying to get her to read stuff, perhaps start by asking her what sort of help you can give her in the few weeks after the caesarean and gently point out that certain things might be difficult. On a similar tack, you could also ask if she wants some help choosing sterilisers, bottles, warmers etc. etc. for bottles - showing her that there is a lot of faffing around with formula as opposed to BF.

It sounds like your sister already knows your views and will run a mile if you try to "persuade" her in an obvious way so perhaps a more gentle way, that could prompt further questions from her, may be your best bet.