Yeah i personally also dont buy it that Jenny and Jackie is the same person, i mean its your relative so how tf you cant recognized her even if she's getting older, i have 5 aunts and 4 uncles from both side of my parents and i can easily recognized each of them even after 30 years the last time i saw them.
That's fair, but people grow up seeing images of family members as they age, even if they don't spend a lot of time together.
I've definitely run into people I knew 20 years ago that I didn't immediately recognize. If someone then told me they were a different person, instead of either having time to figure out why they looked familiar or them telling me who they were, I wouldn't have been the wiser.
So imagine knowing someone for, say, 10 years as one person, then seeing a 30-50-year-younger version of that person, but having a different name attached to that person almost immediately with no way to reference that younger person as the older person ... would you really know who they should be?