happym19- No one is chas vecholilo denigrating your parents but they may have confused putting kugel (and other dry foods like chicken) on TOP of the oven- actually right next to the flame- and putting it IN the oven. The latter would not be allowed on shabbos in contrast to just warming up the food on the stove which is permissible. The yad soledes bo issue would not apply with dry food as it would be “bishul achar bishul”.
