A structural engineer who interprets the drawings and provides a statement/certificate.
I don't see it as anything strange that you need to do this.
We have the same; whoever wants to renovate must produce/pay for everything needed.
Your neighbors should not pay for what you are going to do, just as you don't want to pay for their renovations.
If someone else wants to do the same thing, you can sell your certificate, since you have paid for it.