Melting ice floating on water does not change the volume of the water at all. Melting will have no impact on sea level at all if the ice is already floating. It does have an impact on albedo.

Shelves and on land glaciers are structurally held up. It's when they enter a floating state that sea level rises, and this is the only time ice can cause a sea level rise. If parts of the shelf are cracked, or otherwise the water is supporting them, then they're already floating and so breaking of the parts that are floating will also have no impact.