SubD Triangles

I’m finding it difficult to create a flat subD that is a series of triangular faces all using a single central point (like the inside of a orange). I know it’s possible because I can make a cone, delete the bottom faces, then project the whole thing to the Cplane. Is it possible to:

Convert two points along an edge of a 4 edge (or more) face joined into one point to make a triangle. This new point would retain all connections of the previous two points.

you can stitch points together. you will have an easier time doing this in box mode.

In case you have a boundary curve, a quick way to generate a flat triangle fan SubD is by extruding the boundary, turn it into a SubD and use the Fill SubD Hole command.