Deed split for inheritance tax reasons?

[Mike Lightcap]

Hi everyone, wasn't sure where to post this question so I put it in here. I have a neighbor whose mother was just recently hospitalized for a broken hip at age 90. She is rehabbing now and doing pretty good. This incident has made them realize that mom won't be around for long and they came to me asking if when the time came I'd be interested in buying the house. (Of course I am). The fact that they came to me and asked, I feel obligated to help them out in anyway I can. The one thing I thought they should do is divide the deed between the three sisters and the mother so that when the time comes, they would only have to pay a quarter of inheritance tax instead of the whole thing. So my question is, what type of deed transfer would facilitate this? Thanks in advance, Mike