Can I merge two iMessages with two different numbers?

Hi,

I’m wondering if someone can help me here. My son has an iPhone 8 and (regular phone number) and I have an iPhone 6s(which I don’t think that matters). He recently changed his phone number and upon doing that, all the old text are with that phone (old) number as we’re now texting on the new number.

The question is that I don’t want to get rid of the all the old text he sent me with the old number. Now I have text from him with the new number. Is there a way, I can merge/combine the old text messages (without the old number) with the new number, so it’ll all be in one text?

Thank you

Loyle