(pennsylvania) Water Line Burst And Runs Under An Abandoned Property - What Can We Do?

I made a post here about a week ago (little longer) about how we thought that our water was shut off but not by the water company. Well, we were wrong (and oh, how I wish we weren't.) Whatever gods there are in the world, they looked at me and went, "LOL! You're gonna WISH your problem was that simple."

Sweet and simple: Our pipe burst on the 26th.

Long and convoluted: Where to begin? Our shutoff is not on our street. It's a street behind us. To get to us, it runs under the house behind us. The shutoff valves are located in the same spot. We're really not sure if they are one and the same or not. I don't think that they are the same. Regardless, we still don't know EXACTLY where the burst pipe is, and the plumbers we've spoken to are all... well, it's a mess.

Important information: The house behind us, as far as we know, is considered "abandoned". We don't know if it's ACTUALLY abandoned, or if it's classified that way just because it's VACANT at the moment. Regardless, the people who bought the house do not actively live there and we have no way to contact them. One plumber (local) has told us that they can't help us AT ALL because the busted pipe is "probably on the neighbor's property," but another plumbing company (big business) quoted us $9,900+ to dig up the spot in our backyard "where they think the pipe MAY be burst at," but they didn't use any tools to verify, so there's a possibility that the even if we approved the $10K job, it may not fix the problem.

We have bee without water for, like, 11 days now, and I am on the verge of a mental breakdown because I am *so* stressed over this. Our water company at first told us that they were going to try and see if they could figure out who owned the house and how to get into contact with them (on the 27th), then on the 4th, they turned around and essentially said "the service line is busted, not the main line, so it's your problem".

We've already gone through two plumbers, and while I'm not opposed to calling more out for quotes, at this point, I'm just... I'm accepting the fact that we may have to reroute. We have the water company en route to our house right now to see if rerouting our shut-off is "even possible." (Even possible??? Yes, please, give me more to stress about if it's not possible!)

Anyway. My luck is... not great, so I'm trying to prepare for the worst in advance. Let's say that this ISN'T possible, I already know that I'll have to go through a lawyer to try and contact the neighbors or whatever. There are a few lawyers in my area that I'm considering, but before I even get there... guys, *please* give me an idea of what to expect.

What kind of lawyer do I need for this? What exactly do I have to tell the lawyer, and what do I need them to do? How long do I have to wait after whatever letter is sent? Please help an anxious woman. My nerves are shot over this, especially not knowing how expensive this is going to end up being.

If I need to clarify anything, I absolutely will. I live in PA as stated in the title. My brain is kind of scattered so, please bear with me.

Additional info: Also... getting an excavator into our yard is nearly impossible, and the neighbor's yard???.... there is so much... *flora* if you want to call it that. Like, thickets and vines and stuff in their yard. The yard hasn't been kept up with in a very, very, very long time. I don't even think it's possible to get anything back there.