Reload WhatsApp history from old cell phone?

I have an old cell phone on which old WhatsApp messages are still stored, but of which I have not made a backup (at the time I did not know that it was even possible). However, I haven't used the old cell phone for 5 years. But I still use WhatsApp on my new mobile phone and I also make backups regularly (now I know about the functionality ^^).

My number has been the same since then. Now I would like to make a backup of my old chats as well. Fortunately, the old cell phone still works. I can also open Whatsapp and briefly see my old chats before the app closes again. I can no longer insert my SIM because I already have a NANO SIM and the old cell phone had a normal SIM card.

I have already tried to simply clumsily copy the msgstore.db.crypt8 file from the old phone to the Whatsapp Databases folder on my new phone. But nothing happens there. The old chats are still not visible in the app. I also restarted my cell phone, but that doesn't change anything. Maybe it's because my old phone was a Samsung and my new one is a Huawei?

I have now ordered a SIM adapter on Amazon with which I can switch my nano SIM back to a normal SIM. I can put this back into my old cell phone. I hope that Whatsapp will let me into my chat history on my old cell phone in this way and that I can make a backup of the old messages.

My question now would be whether that would not mean that all my new chats are simply "deleted" when I log into the old history with my number and click on Backup. Because then I hop back in time. Do you know what I mean?

Or do you assume that Whatsapp will then simply insert the old history into the new one. So when I put the SIM back into my new cell phone and open WhatsApp, everything is as before, only that I also have my old chats with me.

Hope that wasn't too complicated!

If you copy a backup from your old phone to the new one, all current, new chat histories are gone.

I don't know of any possibility to "combine" the old and new backup

Thanks for your answer Solomon! I didn't mean, however, that I'm replaying a backup from my old phone. But that I put my SIM card in the old cell phone, go to WhatsApp there and click on Backup and after the old chats are in the cloud, put the SIM card back in the new cell phone. So I don't want to transfer the backup directly to the new mobile phone, I just want to load the old chats into the cloud.

I understood that. But if you then load the backup (from the old mobile phone) from the cloud on the new mobile phone, only the most recent backup (in this case the backup from the old mobile phone) is played on the new mobile phone. Thus, the chat history from the new mobile phone is overwritten and you have just the chat history from old cell phone.

Oh ok, I understand!