HOW TO?

I have a workflow set up and I need to include outside approval from the customer in the loop.  Could I set up 2 different transitions "approval required"/"approval not required" or would it be best to create another workflow and send it out of my current workflow.  If I choose the latter do I have to have the state where I send it out from and a different one where I bring it back?  I don't want to get too complicated.  BTW, the customer doesn't have access to our system, the approval would be manual on our end by email.  I don't want to disrupt our normal workflow to include this step.

Thanks in advance,

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