What will happen if the client doesn't support zap forwards? Will the zaps work as normal zaps (i.e. to the post author)?
Added support for per event zap targets https://github.com/nostr-protocol/nips/blob/master/57.md#appendix-g-zap-tag-on-zapped-event
You can now tag events with a `zap` tag which clients can use to send zaps to somebody else.
Zaps on this post will go to pablof7z@ln.tips (If your client supports this)
Discussion
Yes, forward zaps are optional tags so clients need to support it