Yikes, depending on your jurisdiction, I see all sorts of problems of changing the name on the title. Yes, the taxation issue is big (if a resident of the US) - not an issue if in Canada. However, there is the issue of marital property. You don't mention if your sister is married or common-law. You could be opening up a can of worms providing property rights to the 'bro-in-law' without intending to do so.
Davey and goliath, if there is no Will, you are not a beneficiary. However, you may be his sole survivor, making you his only heir. You need to have a least a 30 minute to 1 hour meeting with a lawyer. This will be well worth the money (and in some cases is complimentary). The lawyer will be able to tell you what you can and cannot do and lead you in the right direction. The lawyer is bound by ethics to tell you what you need to know, however, he/she can also point out the pitfalls of being a do-it-yourself lawyer. But if you go the DIY route, you need to do some research and understand the terminology before you go to the bank or try to change anything, or you will just be butting your head against the wall. Also, you don't mention your jurisdiction... different states/provinces have different laws.