The police and the courts would most likely laugh at them assuming your lease prohibits satellite dishes or modifications without your consent.

Do you know if she would qualify for a modification ? 

@Michael Jones re your example of the wheel chair ... in California, the landlord is required to accept people with any handicap, but the tenant is required to pay for any necessary modifications, e.g., wheelchair ramp.

Before you continue down the modification path much further I'd get in touch with someone who specializes in garage conversions or ADUs and get an approximate price and timeline and run the numbers again, it seems like you may be underestimating the cost, time, and difficulty of a project like this.

Modification usually involves some form of capitalization of the arrearage, plus, perhaps, a forgiveness of some of the arrearage.

The issue is the City of Tacoma.The way the house is currently zoned, it isn't eligable for the detached ADU modifications in the garage. 

I would wait to make any repairs or modifications until he moves out.

That'd be a principle deferral modification, not a reduction.

Someone needs to catch up the payments or one of the heirs can attempt to get a loan modification.

I received a modification to my original offer on my first deal stating that the current security deposits would need to be transferred to the buyer’s (my) designated holder that “shall be a licensed Georgia real estate broker.”