Thanks for becoming part of the Community, cnashncon-outloo.
I can certainly understand how an ability to attach receipts to invoices could be useful and have submitted a suggestion about it as of today.
You can also submit your own feature requests while signed in.
Here's how:
- In the left navigation bar, go to Invoices.
- Click an invoice's Pencil icon.
- Use your Feedback option.
- Enter any feature requests/feedback in the What did you think? text box.
- If necessary, you can attach an image file.
- Hit Next.
- Enter your email address.
- Select Done.

Your feedback's definitely valuable to Intuit. It will be reviewed by our Product Development team and considered in future updates. You can stay up-to-date with the latest news about your product by reviewing Intuit's Product Updates webpage.
As a workaround, our QuickBooks Online subscriptions enable you to add attachments to invoices. If you'd like to upgrade, you can do so any time.
I've also included a detailed resource about working with invoices which may come in handy moving forward: Create & manage invoices
If there's any additional questions, I'm just a post away. Have a wonderful Monday!