Spot on, the multi-address checkout backend is a total mess and constantly breaks tracking sync! Best workaround is placing two separate orders. If one is just under the threshold, use a filler item tool to find a cheap $1 item to hit the $35 mark. Even better, just trigger a free 30-day Prime trial! It completely bypasses the API routing issues on split shipments. Super clean!

I've messed around with Amazon's multi-address checkout a few times, and honestly, it can be a bit of a gamble. I think the free shipping threshold is calculated on the total cart value before you split the addresses, but don't quote me on that. Amazon changes their backend rules constantly. My biggest worry for you is the tight deadline. If one item gets delayed, the tracking for both shipments gets lumped under one order number, and it becomes a massive headache to figure out what is where. If you're worried about losing track of what goes where before you buy, you might want to check out Cart To Link. I started using it a few months ago when I was organizing group gifts, and it's super handy for separating items into different list links before you actually commit to checking out. Personally, I'd be very careful with the multi-address option for wedding gifts. If it was just casual shopping, sure, go for it. But with next week's deadline, I would suggest just bite the bullet and do two separate orders. If the gift order is just under the free shipping limit, maybe find a cheap household item you need anyway and add it to that one. It's much safer than risking a tracking glitch and having your sister's gift show up late.