You can add a text field: "If you would like your donors to include some additional information with their donation, you can use a text field attached to your button to collect it. To do this for a Donation button, you will first need to create a Buy Now button, then edit the HTML so that it looks like a Donate button. Note that PayPal automatically collects the donor’s name and address for you, and includes it in your payment confirmation emails. You will not need to add text fields in order to save your donors’ names and addresses." https://www.paypal.com/webapps/mpp/get-started/donate-button-text-field In the "Enter name of text field" step, you can name the text field "Donation in honor of" and it would show, along with the blank text field to capture that data.
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