If Chara doesn't see Tori and Gorey as their parents, does that mean it wasn't them who knitted the "Mr. Dad Guy" sweater?
It is very likely that Chara knitted the sweater in canon! This is also the case in our AU.
We have always found the additional “Mr” and “Guy” always made “Mr. Dad Guy” sound humorously distant and even a bit sarcastic. In this AU, Chara refuses to call Asgore “Dad” out loud, but made one singular exception for his birthday. Chara made Asgore a dad sweater they knew he would appreciate, but only with the sassy additional modifiers. Asgore treasures it regardless.