Biscuits Bundles works alongside most cart drawer and upsell apps, but there is one common conflict to be aware of and fix.
A bundle has its own add-to-cart flow, because it adds several component products at once. Cart drawer and upsell apps work by attaching their own code to the add-to-cart buttons on your store, so they can run their version of "add to cart" and open their drawer. When that code also runs on the bundle's add-to-cart button, it intercepts the bundle's own add to cart and can break it, so the bundle does not add or the drawer does not open.
The fix is to stop the cart app's code from running on the bundle's add-to-cart button, and let the bundle add itself first. Most cart apps let you do this, either with a setting that excludes or ignores specific add-to-cart buttons, or by turning off the app's add-to-cart takeover so it only opens the drawer.
Note: Other apps' menus, settings and steps change over time and are outside our control. Always check the app's own documentation for the latest, and contact that app's support for anything specific to their app. The pointers below are a starting point.
In your cart app's settings, look for an option to exclude or ignore specific add-to-cart buttons, or to disable its add-to-cart takeover (sometimes called custom add-to-cart, "use theme's add to cart", or ajax cart settings).
Apply it so the app does not run on the bundle's add-to-cart button.
Make sure the drawer still shows the bundle's components neatly (see [Expand items in cart]).
If your cart app does not expose such a setting, its support team can usually tell you how to exclude a button or element, so reach out to them with the bundle page URL.
Rebuy Smart Cart is designed to take over the cart, so it expects the theme's native cart to be disabled rather than to coexist. Rebuy publishes a dedicated guide for bundles: Using Shopify Bundles in Rebuy Smart Cart. See also Rebuy: hide an existing cart drawer. Because Rebuy takes over the cart, making it cooperate with the bundle's add to cart can need a small custom callback, so contact Rebuy's support (or us) if you hit a conflict.
UpCart has an Add to Cart Button Selector setting under Editor > Settings > Advanced Settings that controls which buttons it acts on. See UpCart: add to cart button selector. UpCart's own documentation notes that buttons added by bundle apps may not work even with this setting, so if UpCart keeps intercepting the bundle's add to cart, contact UpCart support to have the bundle button excluded.
iCart exposes the clearest "prevent" controls. Under General Settings > Advanced settings (Developers only), the HTML Selectors and the Prevent Actions options let you stop iCart running its click handling on a chosen button, so you can prevent it taking over the bundle's add to cart. See iCart: advanced settings.
Monster Cart does not have an exclude-button setting, so the approach is to turn off the theme's own ajax/native cart takeover and let Monster open its drawer after the bundle is added, using its documented methods. See Monster Cart: developer methods and selectors and Monster Cart: theme drawer conflict fix.
Slide Cart is similar to Monster Cart: disable the theme's built-in cart drawer, then use Slide Cart's documented methods to open the drawer after the bundle is added, rather than letting it intercept the add to cart. See Slide Cart: installing in your theme and Slide Cart: callbacks and methods.
[screenshot - a bundle added correctly, with components expanded in a cart drawer]
These conflicts depend on how each store and cart app are set up, and the more advanced ones can need a small amount of custom code. Reach out with the cart app name and your store's .myshopify.com URL and we will help you get it working.
