Is there a way to blend the seams of subtools that were merged? Whenever i merge subtools, i have a seam that stays permanent and whenever i build on top of it with polygons then smooth, it shows up again.
Clay brush.
merging your subtools still maintains each subtool as separate geometry. so that seam will pop up, the clay brush as suggested is real good at hiding it.
if you are wanting all your merged mesh to be one piece of geometry your best bet is to retoplogize.
“retoplogize”… what’s that? Saying sorry to retards? 
understand now, thank you.