I don’t see the problem lol. I would just tell there looking really good. Maybe give a few glimpses at their belly, don’t stare obviously just try to show interest. Are you in anyway capable of going out with person? If so like show lots of appreciation for there curves when you cuddle, tell them how beautiful they are and even give them a little belly rub. They’ll get the hint eventually and they’ll probably ask you if you like them more now or if you like big girls? Say yes, but also say that you don’t want to do anything they don’t want to do. This makes your desires clear but you aren’t marked out as feeder just yet. After this become more obvious with your preferences, compliment parts of there bodies that are getting bigger, if you a see a big woman on television say how beautiful they are, begin some light food play. If there not into gaining before this a good way to ease them in. Always treat there gains don’t mention but if they put on decent amount of weight take them someone really fancy, be very romantic in public and if you both drink you’ll probably get away with feeding them the desert. By this point she should be pretty big. If she ever says anything losing weight tell her she doesn’t have too, start just completing worshipping there body and tell them they should do plus size modelling.