We don’t know any PMCs to recommend in the area mentioned, but since selecting the wrong PMC is usually more harmful than selecting a bad tenant, you might want to read our series about “How to Screen a PMC Better than a Tenant”:https://www.biggerpockets.com/member-blogs/3094/91877-how-to-screen-a-pmc-better-than-a-tenant-part-1-services-and-processesWe recommend you get management contracts from several PMCs and compare the services they cover and, more importantly, what they each DO NOT cover.

We don’t know any PMCs to recommend in the area mentioned, but since selecting the wrong PMC is usually more harmful than selecting a bad tenant, you might want to read our series about “How to Screen a PMC Better than a Tenant”:https://www.biggerpockets.com/member-blogs/3094/91877-how-to-screen-a-pmc-better-than-a-tenant-part-1-services-and-processesWe recommend you get management contracts from several PMCs and compare the services they cover and, more importantly, what they each DO NOT cover.

Its not harming me or the neighbors.

@Jeff Langley No harm in recording the option, a memorandum of it anyway, to prevent the seller from selling to someone else.  

Let them stay...no harm, no foul...they are not breaking their agreement after all.

Will it harm a worker?

I sent them a link with a non-chemical alternative method to use a less harmful way to get rid of them, and suggested they take one to a nursery to see if they actually ARE dangerous, advised to supervise their child and dogs, just like they would in a local park, but I'm not about to run back and forth to the property everytime a naturally-occuring plant pops up on the lawn.   

What is the safest way to secure these dishes to make sure there is no harm done to my flat roof?

In the workplace we now have rules against this sort of thing.

We don’t know any PMCs to recommend in the area mentioned, but since selecting the wrong PMC is usually more harmful than selecting a bad tenant, you might want to read our series about “How to Screen a PMC Better than a Tenant”:https://www.biggerpockets.com/member-blogs/3094/91877-how-to-screen-a-pmc-better-than-a-tenant-part-1-services-and-processesWe recommend you get management contracts from several PMCs and compare the services they cover and, more importantly, what they each DO NOT cover.