Making pathways for followers

I made an entire pier including a ship (one of the wrecked ship models in Skyrim) and placed them at Castle Volkihar, where the docks used to be, using "Jaxonz Positioner".

The only problem I'm having, is that my follower will neither follow me onto the pier or onto any of the ship's halves that I put back together.
Using the mod "Your Home Is My Home", I attempted to assign the ship as their home, as it has coffins in the belly of the ship. Whenever I return, my followers aren't on the ship but I would find one standing on a rock connected to the castle.

How do I get my followers to use the wooden walkway and not take another path or just stand idle?
How do I get them to remain and roam around on the ship that I added?

Solution 1:

I am not familiar with the mods you used, but Followers not being able to follow is a Navigation Mesh or Navmesh issue. There are many tutorials available like this one here that explain working with NavMesh in the Creation Kit. There is also this step-by-step tutorial on Fixing Navmesh Deletion Using SSEEdit.

These are modder's resources, and might require some measure of familiarity with basic mod concepts as well as working with the Creation Kit and SSEEdit. YMMV.

Hope this helps.