Merge 2 Whatsapp histories

Hi, my Whatsapp backup (including chats and pictures) was on Icloud. While traveling I changed my IPhone 6 for an Iphone 11. In the new phone I installed all of my backup, including Whatsapp, and was offered to restore my history. I OKd. I was travelling, maybe the wifi at the place I was staying was too low, I don't know, but the following days I noticed that most pictures were blurred. They are not there, I guess the phone backuped again with only the existing downloaded info and so deleted the previous in the cloud before downloading it. But I still have everything in my old phone (minus 3 weeks of added pictures and chats). Is it there a way to merge the info in my old and new phone so I don't lose years of pictures in my old Whatsapp? Thanks!