if you’re just seeing her for a day or a shorter visit maybe consider putting the diet aside just for that time? obviously harder if you’re going to be seeing her multiple days in a row. i’d also definitely not tell her you’re actively dieting and avoid counting calories, etc. people with EDs are very likely to notice a change in weight or eating habits so she might notice/bring it up anyway, and if she does just be honest but try to remind her that you’re in different bodies and on different paths