  A branched covering surface-knot over an oriented surface-knot $F$ is a
surface-knot in the form of a branched covering over $F$. A branched covering
surface-knot over $F$ is presented by a graph called a chart on a surface
diagram of $F$. For a branched covering surface-knot, an addition of 1-handles
equipped with chart loops is a simplifying operation which deforms the chart to
the form of the union of free edges and 1-handles with chart loops. We
investigate properties of such simplifications.
