I've heard of it being done in a steel mill water reclamation system where the original cast iron piping was rotting out inside of cement floors etc due to the corrosive/leeching by incoming low pH waste water.

First, you should have a iron clad signed agreement with your property manager for everything.  

Brown spots on the ceiling, possible roof or pipe leak.Cracked walls, possibly from stress due to the house settling.Rusted cast iron piping, time to replace the line.The list goes on and on.

Most common sewer line issues are tree roots growing into the line, or on older properties cast iron pipes. 

Plumbing, cast iron pipes can rust from the inside out and the rust can cause clogs.

,cast iron waste?

But I already said no way I will cosign on that loan.Yes, that would be my plan getting a bigger house or an actual duplex so we can leverage some of the expenses through rent, but my parents and ironically brother are saying I cant think of that house as an investment because my parents just want a house to live comfortably their retirenment (which makes me ****in mad) because its such an stupid idea especially with our situation.I am extremely frustrated, everybody is making me seem as the bad guy that doesnt wanna help the family because I have my own plans.

Suggestion #2 should be blessed by an attorney familiar with foreclosure in NY to ensure that it would make it faster/easier/cheaper for her to get her house back if she had to.Lastly, be certain to use iron-clad, tried-and-tested Sub2 paperwork!

I never thought about saving first before investing  :/  Ironically enough I found "Building Wealth One House At A Time" on Amazon shortly after and had no idea it was also associated with Bigger Pockets.

That work is going to be a cast-iron b**** to fix passably.