Discussion Process for modifying adjacent meshes to ensure seamless transition from one to another.

For our project, we are procedurally generating several meshes at run time that form tiles of a terrain. In certain areas of our terrain, a higher detail/finer mesh is required. Below is an example of three neighboring meshes (one on the left, one on the top right (the blue one), and another below the blue mesh).
Due to the fact that these meshes do not share all of the same edge vertices as their neighbors, there is a visible seam between each mesh. I believe that the solution would be to add the neighboring edge vertices to each mesh, but I've not figured out how to do that.

I'm sure there will be many ways to solve this problem, but I believe if there is a straightforward way of finding the vertices of one mesh that fall along the edge a the triangles on another mesh, we would be half way to a solution.

I'm looking for any ideas/tips on how to proceed.

Thanks