Assemble high chair at least 2 days in advance. Cut out patterns from cake boards. Brush chair back board lightly with water and cover brown side of board with fondant. Before covering tray, roll 1/4 in. diameter x 24 in. long fondant string and attach with damp brush to outline tray. Cover tray and one square plate with white fondant; reserve 4 in. ball of fondant for chair feet. Let all parts dry for 2 days on waxed paper covered board.
Attach tray supports: cut three dowel rod pieces to 3 1/2 in. high and hot glue to underside of tray (one in center and one at each side); let dry. Attach chair back supports: Cut dowel rod in half and glue each half so that approximately 4 1/2 in. extends from bottom edge of chair back. Cut four 6 in. dowel rod pieces to position horizontally between pillars for chair leg braces; cut rounded ends to fit against rounded pillars.
Decorate bear cake: Ice smooth inside ears and pads of feet. Outline mouth with tip 4; pipe-in tip 6 eyes and nose (smooth with finger dipped in cornstarch). Cover bear with tip 16 stars. For hat, trim sugar cone to desired height, ice smooth and position. Pipe tip 16 pull out fringe; add tip 6 number "1". Pipe tip 21 pull out star on paw; add rainbow nonpareils. Cover cupcake with tip 21 rosettes and sprinkle with nonpareils.
Prepare and cover 3 in. high square cake (two 1 1/2 in. layers) with blue fondant. Pipe tip 1M shell bottom border. Cover second
square plate with blue fondant. Remove fondant from footed area of plate. Turn pillars upside down (scrolled end on bottom). Using reserved ball of fondant, roll 1/2 in. diameter strings and wrap around pillars for chair feet. Hot glue horizontal leg braces; let dry. Position top plate with bear. Edge chair back with tip 3 scallops. Position tray in front of bear. Attach chair back on bear's back with a small amount of icing.
Position cupcake with candle. Print tip 6 name. Cupcake can be used as a smash cake.
The star tip creates the most celebrated, easily accomplished decorations! The serrated edges of the star tip make ridges in the icing as you squeeze it out. Because fill in requires so much piping from the same bag, keep replenishing icing in bag.