Hi Sasha
I've been considering your issue, and I believe using External_ID might be a helpful solution for identifying both the alias and the main profiles. By assigning a unique external_id (a string) to a user profile, it allows for identification across a user's devices. When you first assign an external_id to an unknown user profile, all existing user profile data will transfer to the new profile. Would it be possible for you to assign an external_id prior to capturing the phone number on your end
https://www.braze.com/docs/api/objects_filters/user_attributes_object#braze-user-profile-fields
Hope this helps!