Terrain tesselation

Hi i know this is kind of been posted before but i looked all those and no one gaves a straight solution , i tried everything in those posts , also tried different packages tesselation and no results still are those white edges around te perimeter edge of the tesselation , i tried triangle and flat tesselation , fix cracks and no result.
Need a fine solution fo this , becuase having a big radious of tesselation is not good game will never run well .

I saw some unreal user called bryan talking about that he seems the only person who did it but i need support for this and i want to start this treath trying to be specific in setting and find a solution and for poeple to show if they had make it to show how tehy did it , i know there are plenty poeple out there looking for this to work.

Tried the tesselation copying nodes for supposely packages that does terrain tesselation and did all i can but still this bug white edgy thing.
I appreciatte some guiding o help.