The ornamental design for a crownstiffener with subsidiarystiffener, as shown and described.
FIG. 1 is a front perspective view of a crown stiffener with subsidiary stiffener;
FIG. 2 is a rear perspective view thereof; and,
FIG. 3 is another front perspective view of a crown stiffener with subsidiary stiffener.
The broken lines shown on each edge of the middle seam in the drawings illustrate stitching and form a part of the claimed design. The broken lines showing a baseball-style cap in FIG. 3 illustrate environmental matter and form no part of the claimed design.