LOL!! Very clever.
So, I wonder if she killed the aunt for the finger and this was all a plan to get millions from Wendy's (RIP Dave), or, did auntie die conveniently and the idea came to the niece in a vision at the funeral parlor?
Maybe the aunt's will specified that her opportunistic, moneygrubbing niece was to get the finger?
If she did cut off the finger at the viewing then the niece would have premeditated this as most people don't carry pruning shears around with them.