Accounting wise, you can dig and work some accounts backwards to obtain great insight to any business, this may require an auditor if you are not an accountant, depending on the operation, it might be a good idea to get professional assessments, prior to closing.I say prior to closing as you can make your contract contingent on verified income, expenses, etc. with such being a final investigation after a price is agreed to.

Even if their DOI asks that question, which I have seen, I would expect an affirmative answer to elicit further investigation into the relationship.  

Understand I do not know much about residential financing, so take this with a grain of salt, but it may be worth investigating more:It's going to cost you money to refinance, and the long term effects of the higher rate are significant. 

Unfortunately for you, your immediate interests will not be paramount.Without getting involved you may want to investigate practical alternatives.  

@Cortney ArensteinHello, I am investigating some of the same areas.

If education is a priority be sure to investigate and budget for private education. 

Tell them you will be investigating the usage and will need to bill the excessive usage when you determine who it is.

The trick is to investigate each app and understand it well enough to use it effectively.

If one of the parties "threatened to shoot people", it is the responsibility of the bailiff to investigate the credibility of that threat and if the bailiff is not qualified to investigate, then it is his responsibility to call a deputy who is qualified.  

Attack begets defense.It's easier for folks to attack based on gossip and prejudice than for them to do their own investigation.