Travelling to Germany for work (filming) my son

Dear All,

Hope all is well!! I have a big favour to ask. I'm kind of stuck in the following situation and was just wondering if I could get some advice. Not sure if this is the right place to ask but hopefully I'm allowed to post here.

Basically, my son is 12 and he might have got a small role (not yet confirmed) in a TV show filming in Germany in mid April (for 1-2 months). He is dual nationality, he holds UK (British Citizen) passport and Hong Kong passport. Anyway, the key problem is that his UK passport was expiring in August 2022, my wife submitted his UK passport renewal back in late February 2022. So far, we have no idea how long his UK passport renewal would take to come back, although the UK passport staff told us over the phone that it might take 3-5 weeks to come back.

Questions: -

1. We have been wondering if anyone know, whether it is possible to use his Hong Kong passport to travel and work in Germany? Or would he need any additional visa/work permit? I read somewhere that if it's the UK passport and you are filming, you would have exemption and doesn't look like he would need any work permit...

As I found the following: -
"As of now, citizens of Hong Kong can still travel to the Schengen Zone without a visa. They are granted entry into the Schengen Area countries for tourism and business purposes and permitted to remain in the region for a period of up to 90 days."
https://www.etiasvisa.com/etias-require ... ongkongers

2. He did travel overseas with his UK passport many times before (each previous year), however he had never used his Hong Kong passport. If he uses Hong Kong passport to leave the UK, will there be any problem please? Or can we explain our situation to UK customs that his UK passport went for a renewal and couldn't come back in time for filming project (we could show application status as proof). He does have UK birth certificate which we will also bring along as well. Does anyone know whether this would work out please?

I would be really grateful!

Thanks a lot!
Tony

Can't comment on the specifics of working in the EU.
I assume a Hong Kong citizen doesn't need a visa to enter the UK? If one is required the airline will want to see a valid visa or BRP residency card, otherwise boarding will be refused.
If HK traveller doesn't need a visa take a copy of son's British passport, and even a prior expired one, take that with you and explain when you return .
A birth certificate as such is not proof of citizenship. Note that a British citizen has automatic "right of abode" in the UK so can't be refused entry though it may take a bit of extra time. This is an issue many newly naturalised citizens are now facing because of the long processing time for passports, and wishing to travel...