I had BBM on both my Q10 and Samsung note 3, both with different BBID and PINs. I however changed the ID on my Q10 to the same one on my Note 3, with expectation that it will prompt that my note 3 BBM contacts will be automatically transferred (That was the main intention as only very few contacts were on the Q10). Surprisingly, the BBID change was successful but it never moved the Note 3 contacts. I have subsequently done a security wipe on my Note 3 but can’t get back the BBM contacts. Is there a way I can restore my old contacts, I know the BBM PIN for both phones.
If you know them the only other way to restore them is just to manually add the PINs if you happen to know them.
Your BlackBerry ID stores all the PINs you've added, there is no way to merge them though. So if you had lets say 10 contacts on the Note 3 BlackBerry ID and 5 contacts on the Q10, when you use the BlackBerry ID from the Q10 on the Note 3, it will only show 5 contacts (from the Q10 BlackBerry ID). So if contacts are on two different BlackBerry ID's, you need to use one BlackBerry ID and manually add the contacts there.
When you switch BBM again, it will carry over the contacts.