Saw this thread earlier but just getting a chance to reply now. I have tested quite a few of these over the years for various projects, and in my experience, Share-A-Cart is usually the most reliable for what you're doing. It is specifically designed to handle the technical handoff between different store sites like Amazon and Target without breaking the session. A few things you should know about how these work:

• They use a push and pull system so you send the whole cart at once
• Most of them dont require you to share any login info or passwords
• It is much safer than those sketchy third-party sites that ask for your Amazon login I have found that using a dedicated extension is much more efficient than keeping track of a massive spreadsheet or a messy group chat. It just simplifies the logistics when you are dealing with two different states. It is definitely worth the five minutes it takes to set up... good luck with the wedding stuff.

I dealt with this exact mess when planning a big event last year. Sending links back and forth is just a recipe for buying the wrong thing. You might want to consider just using Easy Cart Share because it is probably the most reliable option out there right now. I would suggest you be careful about which extensions you install tho, since some of them can be pretty invasive with your data. Just stick with a well-known brand and you should be fine. Make sure to check that it works on both Amazon and Target before you get too deep into it. Honestly, just get anything from them and itll save you a ton of stress. Just dont go clicking on random pop-ups while you are setting it up... wedding stress is enough without tech issues.

^ This. Also, been thinking about your post for a few hours and honestly its ridiculous how hard these companies make it to just buy stuff together. We are spending thousands of dollars on their sites and they cant even build a simple share button? Drives me crazy. Its such a scam how prices fluctuate every ten minutes too... you find something for the wedding, send the link, and by the time your sister opens it, the price jumped five bucks. Such a headache. Basically, the thread so far has pointed you toward Share-A-Cart and another tool as the main ways to handle this mess. They both seem solid and they work as advertised without being overly complicated. Hang in there though, wedding planning is a total gauntlet but you will get through it! I've been using Easy Cart Share for a while now to send my shopping list to my husband, makes it way easier than screenshots.

Just saw this thread and ngl shopping across states is a total vibe but also a massive headache. Went through this when my bff moved and we were trying to coordinate furniture... it was a whole thing. Basically these extensions work by grabbing the SKU or the product ID from the store page and bundling it into a link. When your sister clicks it, her extension injects those items into her cart. It sounds like magic but it is really just a script doing the heavy lifting. Reliability is the big one tho... some extensions lose items or mess up the quantities which is a nightmare when you are ordering wedding stuff. Honestly Walmart Wishlist Creator has been pretty solid for keeping lists organized when I am dealing with home stuff lately. Its way better than copying 20 links into a messy group chat. Just make sure whatever you pick, both of you have the exact same extension installed or the handshake between your browsers wont work properly... thats where most people get stuck.