We are all familiar with issues related to service animals (specially trained and certified dogs) and assistance animals (such as emotional support animals of any species or breeds).This post suggests a compromise response to those issues.Landlords who prohibit animals do so because theyfear the damage that might be caused by those animals, know it is highly unlikely they will be able to fully recover compensation from the tenant if there is damage, and fear litigation if the animals harm someone. 

But as one of the OP mentioned if your intention is to subdivide this and you have all these neighbors close to you.. then you need to go into mediation mode and make sure you have them as allies and not enemies they can cause you far more harm in the land use process than simply bugging you about walking on your property.. the cost of perfect some silly  right to walk on your property is far more than anyone is going to spend in the real world unless your land locking them.

Also, I know you already told them NO, but for future knowledge, never agree to any remodeling while a tenant is in a unit.....the potential of harm and lawsuits is not worth it. 

Pitbulls and other dangerous breeds will require risk insurance at a higher premium and will open you up to legal problems if the harms someone. 

You ARE responsible for the harm your tenants cause neighbors.  

If the building has 4 units or less and the landlord lives in one of the units.If the property is a SFH and the owner owns less than 3 SFH's.If the animal brings an undue financial hardship to the landlord.If the animal causes damages or harm to others in the building.

Being listed as an additional insured does absolutely zero harm to you, however it does protect you in the amount of the liability coverage on that policy and it also pays all legal fees up to the point when the limits have been paid out on the policy or the claim is denied.

Real risk of harm to others, not just defaulted rent and property damage.  

In California, the eviction process focuses heavily on the substance of the eviction paperwork.

People who have this addiction are more likely to gravitate toward other addictive substances too, like drugs and alcohol.