Your objects seem to be SubD’s.
As mentioned here, you can use SubDFuse in Grasshopper and QuadRemesh to do this.
The fusion works just for two SubD objects at a time. You’ll have to do the fusion in sequence for all your platforms.
Doing this with Grasshopper allows you to use SubD’s with vastly different subdivisions and do changes basically anytime. Make sure to also check the new Sharp command in Rhino 8 WIP.
subd_fuse_quad_remesh.gh (29.2 KB)