"if statements" in Patterns?

Is it possible to put “if statements” in Patterns? Like, “if this Pseq plays, then play this other Pseq”?

You can use if statements e.g. with Pif or within Pfunc, which is an idiomatic syntax within Pbind.

In a strict sense of the wording this is totally impossible because a Pseq - and even a Pbind - never play. They are stateless templates for other objects - Streams and EventStreamPlayers - that are waiting for polling demands and resp. are played.