@Nicole_N 

RE: I understand how frustrating it can be when things take longer than expected. Your time is valuable, and it's not our intention to keep you waiting for a solution.

Of course it is. It's exactly Intuit's intention as you have chosen to not add this ability.

RE: I know adding signatures to checks is vital to your business and would help many customers as well.

It is great that you know this. You should tell someone who can do something about it.

QuickBooks Desktop has had this ability for 20 years.

Intuit continues to insist that QuickBooks Online is a reasonable replacement for QuickBooks Desktop. This is one of the few hundred or so reasons it isn't.