So 100% get not announcing a pregnancy at a wedding/someone else’s event etc. But this is in-laws we are travelling up to see for an informal birthday event, but a milestone birthday. Event isn’t the day of birthday and is a drop in/out type thing. We want to tell them first before other family members, so wondering how it would go down if we told them at a time there was no one else there apart from us? They wouldn’t have to tell anyone else, or would it over shadow their day? We are travelling on afterwards and won’t see them in person for another few months maybe so it would be over the phone if not then.
YABU - don’t tell them in person, wait and tell them over the phone
YANBU - tell them if you see them with no one else there