To merge elements in the Main Menu select Model -> Operation -> Merge.
Arguments:
vertex 1a: vertex of the quadrangle quad 1 to merge with the vertex vertex 2a of the quadrangle quad 2.
vertex 1b: vertex of the quadrangle quad 1 to merge with the vertex vertex 2b of the quadrangle quad 2.
The dialogue box to merge two quadrangles is:
Merge two Quadrangles
Arguments:
vertex 1: vertex of the edge edge 1 to merge with the vertex vertex 2 of the edge edge 2.
The dialogue box to merge two edges is:
Merge two Edges
Arguments: 2 vertices (vertex 1 and vertex 2).
The dialogue box to merge two vertices is:
Merge two Vertices
TUI command: Merge elements