IMO, you need to be careful with morphs when you get near seams, the transitions are not the greatest. I usually stay just outside the seam and make do with what I want or...
go hog wild and blast right through it. lol!

If the latter, then only experience will tell you what you can and can't get away with. But you will need good textures to hide that area. You probably don't want to hear this because it has taken you some time to get to where you are but you shoud try, staying just outside the seam, going through the seam ever so slightly, and then blasting right through it...then create those morphs and see how they affect the mesh.

Good luck, hope this helps.

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