MIL was German and FIL was not so MIL had to give up her German citizenship on marriage. DH was born pre 1975 so it looks as if he is eligible to claim German citizenship under the 2021 changes and that my DC are also eligible. I suspect the siblings and their DC will also want to claim this. Has anyone been through the process - how complicated is it - we have everyone's birth certificates and MIL's marriage certificate but not her German passport - will the birth certificates be enough?
Are there any reasons not to claim citizenship - I can't think of any.