Hello GarciaM,
Thanks for connecting with us here again. Managing your invoices and estimates in QuickBooks is a great step towards keeping your books clean. I'll be happy to share more details about the estimates and invoices so you're on the right path.
The QuickBooks workflow works in a way that allows you to convert an estimate into an invoice and not vice-versa. That being said, you'd have to manually add the the products in question to the estimate and if you need to convert the updated estimate into an invoice, check out the following article: Convert an estimate into an invoice in QuickBooks Online.
Let me know if this info helps. I'm here in case you have additional questions. Otherwise, I wish you a great rest of the week.
