There is another twist to this for me, my wife and I both have multiple cities two of which are on the same world, in the beginning we could not put FP on each others GBs, at some point that changed and has not been an issue for quite some time, it was never a big issue for us,
However, for some reason my wife gets discounted Diamond offers very very frequently and I have never got even 1 discount on diamonds, she has had 3 in the past 10 days. I have always figured this had something to do with us being on the same internet connection somehow. I got so annoyed I contacted support about it and they said it is all determined by the software and that they have no control over the software. Just a thing I have learned to live with.