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One thing you need to realize if they use two different phone numbers that alone may keep that from happening. But again unless you use my local method I just dot see it happening. And even if you do get it over they will likely not be used for future messages from those contacts because it’s a different phone number now. You’d have two strings depending on what phone number it’s coming from.

You may have a chance with the dual phone number on some iPhones. Not sure how that works with regards to messages but you could look into it.
 
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