Hi ,
Having your mesh on the grid will give you better results for this definitely. When you setup your grid if you set up the vertex snap for your UV to target a 128 lightmap resolution, any resolution you use above that (256, 512, 1024) will not have to have the lightmap UVs redone. (The snap grid spacing you’ll need for 128 is 0.0078125)
This is where the world settings come into play with lightmass and being able to reduce the seams using Indirect Lighting Smoothness and Quality.
I know this was mentioned in the other thread but the reason the seams are there is because lighting is baked on multiple threads that cause this issue and by having an item combined in your modeling software it can keep these items being baked on the same thread.
This definitely is a good way to give a quick test and see what the lighting bake should resemble but it’s good to remember that movable lighting isn’t baking anything into a lightmap. You may already know this but in the event that someone else reading doesn’t. 
Give the grid snap in your UV a shot and if you’re still having issues please let me know!