Would not have worked had you not updated birthday. They verify accounts match by Name, birthday and email address. Why should they let you go any further if it wouldn't work anyway
I just want to put this out there: In order to combine avios to IB you need to have at least 1 mile in the account. So if you're moving from IB to BA leave 1 mile in the IB account if you'd like to ever use it. If not you'll have to do an MR xfer or buy points from them at .2+ pp
Oh, crap... NOW you tell me?!
Seems like you still can but I'm sure what the cutoff time is. I've had too many accounts that this happened to.
I'm not sure that it's necessary to have 1 point in the account. I think it's just necessary that the account is 'active', i.e., it has had activity within a certain amount of time (earning or redeeming).
Which points? All of them, or the extra?