The larger brokerages are all paying $20-$80m settlements and small brokerages have no protection if this ever comes for them.

My sister is selling her house to me; however, we want to do a mortgage transfer since she currently has a 2.5% interest rate, but the bank will only pay what is owed on the current mortgage.

As to paying off mortgages,  most rarely pay as agreed over 30 years.

That would be a little higher than I would care to pay. 

One San Leandro landlord is owed $132,000 in back rent and in Oakland you can't discriminate against rental applicants with a criminal back ground (except sex offenders) and several stories of non-paying tenants which took thousands in legal fees to evict in Oakland. 

Should I just contact my attorney if she does not pay rent on the 1st?

Not only covering the rental income in cases where the dwelling is uninhabitable but more so if the tenant defaults and stops paying rent and has to be evicted.

So, you end up paying money to file the lawsuit which gets added to what they owe.

Here's my situation:I own a duplex that is about 100 years old and my tenants pay for all of the utilities EXCEPT for city water (which comes out of my pocket each quarter).Both of these rental units could benefit from some plumbing updates throughout (e.g. - 1.28 gallon toilets, eco-friendly faucets, eco-friendly shower heads, etc.) as a way of helping this rental property consume significantly less water (enough to save me a few hundred bucks each year...

It sounds like you told her to pay yesterday, but didn't ask if she could pay.