For your 4 ZP products (does not matter when you submit), you’ll get 4 30% discounts for a single item that can be used at any time. Note that a ‘single item’ does include the sets and packages Sonos offers.  So for example, a set of Arc + Sub + 2 One SLs would count as a single item and only use of one of your discounts.

Nah.  The timing of when you use submit a ZP for discount doesn’t matter.  You can do them all now and use the discounts whenever you please.

Yes, you can use them as you please.  Use them as a separate S1 system, sell them, recycle them, etc.  Note though that if you do sell them, probably should let the buyer know that they are no longer eligible for discount.

If you submit all 4 into the upgrade programme, then you will have 4 separate 30% discount credits available.

Each 30% credit does not have an expiry date, so they can be used at different times/orders.

Although the credit only applies to one item, if you purchase a set (for example, Arc, Sub, Ones), a set counts as one item, so the discount applies to the total value. If however you purchase the Arc, Sub and Ones as individual items (even in the same order) then that would require 4 upgrade credits.

Your existing Sonos devices will continue to work on S1 as they do today.

If you were considering to sell your S1 devices at a later date, you will attract a premium price if the upgrade credit is still available on them, so I would only elect to upgrade a device when you know you are going to use the credit yourself.

Thank-you to @melvimbe that’s all very clear.

And thank-you @Mr. T for the suggestion to not submit the items for Upgrade until I’m ready to change them in case I instead decide to sell them with the upgrade unclaimed.

Thanks both for clarifying that I can still use the ZPs on a separate S1 system.

Can I mark both a best answer!

Give it to Mr T, as he had a good point I hadn’t thought of.