I really don't understand how that replay protection thing works. I get the idea, but I'll need to dig into it.
As long as you have an input that doesn't exist on the other chain, the transaction can't be replayed there. I can send you some "dust" to ensure it can't be replayed, just give me a BCH addy and add my dust to your transaction.
Disclaimer: this might compromise your privacy by exposing your addresses. It's up to you if that's worth it.
OK, I think I get it now. I just swept all my old addresses to new ones in the Electrum Cash wallet, meaning that any transfers I do with these new addresses won't effect the balance of my old addresses in the other forkcoin chains, right? The fact that the old addresses still hold the coins in BCHA seems to confirm that (just double checked at blockchair)