In a property settlement case you will be asked to lodge a financial statement, one of the questions on there is what is the income and relationship status of any other person that lives with you. They also ask you to declare any, loans, property ect that you have and this includes anything you currently share with any person.
The court may use that info to look at each parties current financial/living conditions to asses if one party has a greater need then the other.
My partner was served with property settlement papers recently and I refused to provide my income details, they can sopena me to provide it if they want it. His ex will likely try to claim that she needs a greater share of the settlement because his current circumstances are better then hers because he lives rent free in a house I own.
They most certainly do. In my case they sopenad my new husband's financials going back to before we even met. We had submitted all his financials but they wanted proof. it is all about the 'just and equitable' step where adjustmennts are made in favour of the party with the least.