I've always thought that [happen to] is the phrasal verb indicating chance, which can be replaced as [by chance] such as...
I happen to have some money in my pocket.
= I have some money in my pocket by chance.
Do you happen to be a teacher?
= Are you a teacher by any chance?
But, sometimes I stumble across what I can't use the above rule. For example...
A,B,C are at the table where B prepared a meal for C.
A: (Went ahead and tasted some) It's so good!
B: Hey! Don't just eat it without asking! This happens to be for C.
Here, the meal can't be something prepared by chance, more like it's fixed by B on purpose. Then what's the exact meaning of [happen to] in this sentence? And what would you recommend as the alternative words rather than [by chance]?