I've got a rather long and convoluted question, so I'm going to try and explain everything, so I apologize for the rather lengthy post.
Starting in January 2017, i was living in the USA on the J1 visa programme, working as a visiting academic at a higher education institution. This visa was originally planned to be for 4 months. However, my visa sponsor / organisation I was working for decided to offer me an extension of my status, i.e. the DS-2019 form for a further 3 months.
Furthermore, my organisation offered me a longer-term, new post as a visiting academic, for which I had originally planned to leave the USA on the 17th of August (3 days before the expiration of the grace period on my DS 2019), after which I would have gone straight to the U.S. embassy in London to get a new J1 visa, and return to the USA on the 1st of September 2017 to start my new position as a visiting academic.
All the above was done using my BRITISH passport, I also have a passport and citizenship from GERMANY.
However, life happened in between, and in late June, my father, residing in Germany, fell ill, so I had to travel to Germany at very short notice on the 26th of June in order to be with my parents. My father has since passed away.
My visa sponsoring organisation has provided me with a new DS 2019, and I have since also paid all the relevant fees (SEVIS & embassy appointment fee), and booked an interview appointment at the American Embassy in London for the 25th of July.
However, it would be of huge importance for me to travel to America on the 28th of July (I already have a booking), in order to have a short vacation there, and especially in order to go to a concert of a band that my father and I both loved very much, and I promised him that I would go to this concert before he passed away.
Now, here's my question - will it be OK for me to depart Germany on the 28th of July, and enter the USA on the VWP using my GERMAN PASSPORT, after which I'll return to Europe on the 17th of August, and return again to the USA on the 1st of September on my BRITISH passport using the J1 and DS 2019 procedure?
My planned trip for August is a tourist trip, I have a ticket to return to Europe already booked and can present this upon entering the USA. Furthermore, I will not be setting foot on the campus of my sponsoring organisation, or engage in any activities which I would be doing, were I already there under the J1 programme.
Is it OK for me to be doing this?
Should I speak to the US Embassy in London and inform them of this plan?
Should I be expecting any kind of confusion at the border as I plan to be entering on a different passport than I've used the last few times?
How can I be as transparent as possible about this?