How to scale a part of an object without influence parts around it

Hello, i’m trying to create a Geometry Node that allows the user to create a window based on a blockout pre-created, so i have modeled a " base window " mesh that will fit to the size of the blockout, but if i just simply scale it, it causes the window to stretch on its sides, so i’m trying to see if there is a way ( cf screenshot ) to lock window corners, and scale the junction between them, because this part would’nt be stretched.