Adding new users to Adobe Sign who already have Adobe accounts

[Ben28635876dzv5]

I've just set up Adobe Sign solutions for enterprise for our business. I'm now starting to add users. The problem is that a number of our directors and managers already have an Adobe account. So when I add them as a user in Adobe Sign they end up with two different accounts. This creates a lot of confusion!

Is there any way of adding a user's exisiting Adobe account to our Adobe Sign? Or is there a handy user guide for switching between accounts?

Thanks!