How do I handle this tenant dispute?

[Nicholas Olson]

I have two tenants living side by side in a triplex  who are at each others throats and they are relying on me to settle the dispute.  I just acquired this property two months ago and it's my first time being a landlord.  I'm not entirely sure how to best handle this.

 Allegedly the children of one unit are bullying the children in another unit and their parents are self disciplining the other units children.  As you can imagine this has led to some pretty upset parents, and it's hard for me to determine who is actually more in the wrong and what to do about it.  It's sort of a he said she said where both tenants are from what I have been told, going out of their way to annoy the other tenant.  From parking in an annoying manner to use up extra spaces(I have no parking lines in the dirt parking lot) to banging on the walls of their neighbors to yelling at each other outside.  

I don't want to get in the habit of micromanaging tenants personal issues, but at the same time I want to provide a safe welcoming place for people to live.  Banging on walls, verbal abuse, and improper parking in an already small parking lot isn't something that I want to set a precedent of being ok to do. So, how would you handle this?  3 strikes you're out? Ask for video evidence of alleged banging on walls? How do you cut through the he said she said to find out who is actually at fault?

Things to keep in mind. This is winter in Maine, painting parking lines in a snowy parking lot is out.  Doing an eviction this time of year may be necessary but only as a last resort.  The PO had leases that rollover in the summer, I acknowledged that I would honor those leases but have not had anyone sign new leases, so basically everyone is month to month at the moment.