Responding to a mulligan

By ROTBI, in UFS Rules Q & A

I didn't see anything in 5.4 about this: Is it ever possible to respond to a mulligan? I'm assuming that step counts as being before the game itself so you can't respond with abilities reading something to the effect of "when you (or your opponent) discard cards..." or "when you (or your opponent) remove cards from the game...". Am I correct?

ROTBI said:

I didn't see anything in 5.4 about this: Is it ever possible to respond to a mulligan? I'm assuming that step counts as being before the game itself so you can't respond with abilities reading something to the effect of "when you (or your opponent) discard cards..." or "when you (or your opponent) remove cards from the game...". Am I correct?

Correct.