I claim the ornamental design for an adjustable monument frame with slide on accessories, as shown and described.
FIG. 1 is a perspective view of the adjustable monument frame with slide on accessories showing my new design
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a right view thereof;
FIG. 5 is a left view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a view to exemplify how it would be placed on a headstone and decorated. Portions as shown with broken lines do not form any part of the claimed design.