Thanks for joining us here in the Community, @johnfromnyc.
I'd like to inform you that at this time QuickBooks only allows you to add up to two custom fields on the invoice template. Thus, being able to add the employee's name to automatically fill in on the said field isn't available.
To get your work done, you may follow the workaround presented by RaymondJayO above.
I hear you and realize the importance of being able to acquire this option. Know that our developers are constantly finding and considering new ways to cope with your business needs.
To stay in the loop with our latest news and product road-maps, I encourage you to visit our QuickBooks Online Blog site regularly.
Lastly, you can always scan through this reference to give you more tips when it comes to modifying your sales template in QuickBooks Online: Learn how to personalise your sales forms and add the info that matters most to your business.
I'm just a reply away if you have any other concerns, @johnfromnyc. I'd be more than happy to help. Take care!
