I Just Found Out We Don't Own The House We Have Lived In For 15 Years. What Now?

Location: Ontario

I live with my mom and my stepdad. They bought this house around 15 years ago and have been paying property taxes, doing renovations, paying bills, and all the things a home owner would. The property has 2 parcels of land; the back property and the front property with the house on it.

Recently we were thinking about selling this and my sister's house and buying a large property where we could all live together, like a multigenerational property (my mom and stepdad, me and my sister, my sister's kids). Imagine our surprise when we try to get a quote on this house only to find out that we only own the back property, and not the property with the house we are currently living in.

When we looked into it, the couple we bought this from ALSO didn't own the house. The house belongs to a couple we have never even met, and in the 15 years of living here has never made contact with us.

We spoke with the lawyer who was involved in us purchasing the house and they said they are going to look into it. It sounds like they think it is a deeding issue and are going to reach out to the couple on the deep to see if they will sign it over. She said worse case is we will have to go in front of a judge.

So, I guess I want to know if anyone has ever been involved with something like this? What should we expect? Are we going to lose our home? My stepdad is retired and my mother is currently not working, I don't know what we would do if we lost it all. Any advice would be appreciated.