I wouldn’t do it.
If you worked at Target, would you even consider doing a four-hour shift gratis?
In honor of your boss’s anniversary, birthday, etc.?
Besides it is always best to gift down, not upwards.
They likely are not expecting anything from you, but if you feel that you MUST do something perhaps help your charge(s) design + create a loving, homemade “Happy Anniversary” card for their parents.
Maybe bake some cupcakes w/them too!!
