The ornamental design for an uppertray for babywalkers, as shown and described.
FIG. 1 is a perspective view of an upper tray for baby walkers showing my new design thereof;
FIG. 2 is a front side elevational view thereof;
FIG. 3 is a rear side elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof;
FIG. 8 is another perspective view thereof; and,
FIG. 9 is a further perspective view thereof.
The broken line showing of the bottom support structure in FIG. 7 and the walker base in FIG. 9 is included for the purpose of illustrating environment and forms no part of the claimed design.