The current transfer option in QuickBooks Online only allows us to record transfer on a single transaction. If you need to record multiple bank transfers, you'll have to keep recording them one at a time or can create a recurring template. If you need to match multiple transfer to a downloaded bank feed. You'll have to record each transfer and click on Match or Find match option in the Banking screen.
I can definitely add this to our report and let our product development team know of this option. I recommend also sending your Product feedback in product, through the Settings icon and select Feedback option in QuickBooks Online.