Who shoots the free throws?

[Camron Rust]

Yes.

I don't think anyone would debate that A is due FTs regardless of the condition of A1. The only question, as you've asked, is which player shoots them.

Normally, A1's sub will get the FT's and that sub is chosen by the coach. At least in some degree, it is established that the coach gets to choose who gets to shoot the FTs. I think it follows, even in absence of a direct statement to the fact, that the coach also gets to choose who gets to shoot in this case.