Merge SMS with iPhones

I’ve 3 iPhones and I would merge SMS, but I noticed that with Backuptrans SMS Transfer isn’t possible because these iPhones have a different version. My iPhone 4S has iOS 9.3.5 and others iPhones have a version over iOS 10. So, with this software isn’t possible merge SMS because I think that configuration of file DB (about SMS) is different (configuration DB SMS file of iOS 9.3.5 is different than iOS 10 and over). So, which is the best solution?