It looks like you've got a solid start on your Welcome Flow, and your approach to separating new subscribers based on whether they've made a purchase is a smart move. To ensure this setup doesn't clash with your post-purchase flows, you can use a combination of conditional splits and flow filters effectively.

First, it's important to understand how Klaviyo processes these flows. Conditional splits in your Welcome Flow, like the one checking if someone has placed an order, are evaluated based on the customer's actions at the time they enter the flow. This means that if someone triggers the Welcome Flow but then makes a purchase, the conditional split might not update their path unless it’s re-evaluated.

To prevent overlaps, you can set up a flow filter at the beginning of your Welcome Flow that checks if a customer has placed an order in the last X days (e.g., 2 days). This way, if someone makes a purchase immediately after subscribing, they'll be filtered out of the Welcome Flow and won't receive duplicate messaging from both the Welcome and post-purchase flows. Additionally, using time delays before applying conditional splits can help ensure that recent purchasers are correctly filtered into the appropriate flow.

In your post-purchase flow, consider using trigger splits instead of conditional splits. Trigger splits evaluate actions specifically related to the flow’s trigger event (like "Placed Order"), ensuring that the flow accurately reflects customer actions taken at the time of triggering the flow. This helps in maintaining the flow's accuracy and preventing any overlap with other flows​ (Klaviyo Help Center)​​ (Klaviyo Help Center)​​ (Klaviyo Forum)​.

By combining these techniques, you can create a seamless experience for your subscribers without any redundant messaging. If you need more detailed guidance, check out Klaviyo's articles on flow branching and post-purchase flow setups​ (Klaviyo Help Center)​​ (Klaviyo Help Center)​.

Hope this helps :)