Can I use proceeds from selling an iPad and MacBook to purchase a new MacBook?

You may set up a trade for credit toward a new Apple device or credit on a gift card IF your trade in device has any value.

This is a link to information about Apple's Trade-in program:

Apple Trade In - Apple

Yes and if you choose to purchase directly from your local Apple Retail Store, then you can trade-in after purchase.

The reason is simple:

1. Purchase your products.
2. Set it up at home and transfer everything before you trade.
3. Erase your old devices.
4. Trade-In at your local Apple Retail Store at your convenience.
5. You will be offered an option for a gift card or credit (with sales tax included) to your original form of payment.

Let me know if you have any further questions.

Good luck! 👋🏼😉