I have a request from a client to do approval routing on a document. First request like that in 6 years. I know the OOTB configuration is pretty straight forward. Here is the curveball, they want to do parallel approval for the first task, where only 1 of the two users has to approve the request and then it would move to the next task, which is a serial approval with one user. After doing some research, I was able to do the parallel approval by one user with changing the workflow completion code in SharePoint Designer. The issue is that after the approval it completes the whole approval process without moving on to the next task, single user serial approval. Can anyone help, been wrestling with this for a week.
Try reading through the MS instructions on this. Perhaps this video might help too, you'll find quite a lot online. In this video there is a part on completion conditions, I'd recommend watching the whole thing as it's a clear video, but in particular watch from 7m 15sec. I think this should help answer your question.
Perhaps the completion of your parallel workflow could be used to initiate a separate serial workflow?