Can I Sue My Neighbors Title Insurance For Septic System Encroachment Issue?

My husband and I purchased a home 2 years ago and did not have a property survey done prior to purchasing. We were told by prior owner that they owned 20 feet behind our existing fence where a hill lied and currently butts up to our fence. We got a property survey done a few months after purchasing as we had a boundary line dispute with our neighbor. After we got the results of the survey, we find out said hill is actually our neighbors septic system which is sitting 20 feet over the property line on our property.

We have been a lawsuit for a year and had mediation today. We have been fighting tooth and nail to get them to move it completely off our property as they do not want to do so. Anyway, their title insurance company had a representative at the meeting today. We were wondering why and our lawyer said it’s to cover themselves.

The entire reason why we are in this situation is because the title search from my neighbor failed to pull any documents associated with their septic system when they bought the house, which if caught would have shown that it was installed incorrectly originally (the septic installation company was negligent and we have proof as they physically labeled the proposal sketch that the septic system was on the east side, which in fact it is on the west, no property survey was attached as well).

We have spent over $10k on our law suit, and it is projected from my lawyer to end in the $25 to $30k range if it goes to trial. We have also been though much pain, suffering and turmoil due to harassment over the past year and a half from our neighbor which stems to said lawsuit (can’t leave my home without being recorded, steals my kids toys if they are close to the property line, things like this). I also have personally put a lot of work in myself as Neighbor had submitted a proposal to “settle” from the original septic installation company, but proceeding with this proposal would cause a community health hazard as I had an engineering company review and they stated that uncontrollable septic sewage would spill into our property and the ditches when we go to level out the 60 x20 area to be level with our existing property. The county revoked the original approval they gave for this proposal, so now they have to go back to the drawing board.

Our title insurance stated they would have nothing to do with the claim as they would have not found this issue with their title search on my property. Do we have grounds to sue my neighbors title company for negligence as well as the original installation company?