@Clclow You would need to negotiate the previous provider to give you a temporary activation to complete the number transfer, although I'm not sure if that will be possible without your having to pay to reactivate those accounts to do the transfer. Depending on how important those numbers are for your family members, you could decide to take a new number from PM instead, especially if the previous provider won't allow temporary activation without payment.
Here's a post from another customer who was able to get his number transferred (edit: from a deactivated account) which might be helpful in your case as well, although YMMV: https://productioncommunity.publicmobile.ca/t5/Get-Support/Issues-with-cellular/m-p/904808#M618760
edit: @Clclow It could be a bit more complicated in with your accounts since it looks like you've got rid of the old SIM (just re-read your post), however, I've read other posts where the previous provider was able to accommodate the transfer without the SIM (perhaps email confirmation, not sure), but the porting # would need to be involved, so call the number already provided to see if that's possible.
