And they said the dogs never went in the guest room, but as I'm allergic it was pretty obvious that was not true.

Quite a few people are allergic to cats. 

A lot of people don't like the smell on a lot of people are allergic.

I received a call from her lawyer who insisted that he could get "approval" letters from the other tenants stating that they are not allergic and that they are okay with the cat.

If she's seriously allergic enough for it to be a disability, then she can provide proof with the letter. 

So we've expanded to commercial or commercial retailWe seem to be allergic to selling any of our 6 rentals, , so instead, we somewhat cannibalized our current cashflow, to get some capital out, to apply to our primary residence(in Canada our primary residence interest is not deductible)We've paid off all but $75k of our $550k primary residence and have a $355k HELOC at our disposal(which if we use for investing, becomes deductible interest).We've found 2 individual neighboring properties.  

He is allergic to cat dander and the house has so much inside, in the attic, in the yard, garage and underneath the house he got instant sinus problems and severe rashes on his entire body .

.- Your property should be in my comfort zone which in my case includes: Well above my minimum $80k including rehab loan size (the more the better), not too rural (seriously no McMansions somewhere in outer Hicksville - nothing against people living there, my underwriters seem allergic to wide open spaces), no groundups or land or mobile parks.- Please don't come to me saying that so and so has offered better rates or less points or less closing fees.

Yikes, this is one of those situations that absolutely makes me cringe (several family members are deathly allergic - and this is not something to play around with).

Just as a home buyer will have a home inspection, it would not be a bad idea (if your family is averse or even allergic to certain issues) to have a mini-inspection by a Home Inspector.