Honestly asking for an opinion from an outside source. love seasons
I would go and watch the movies. You want your girls to see them, and that is a very good thing to do for them. There may well be a price to pay in terms of your sister's behaviour, but you can be aware now of what she might or might not be doing.
If that is all too difficult, maybe you could investigate ways of turning the movies into DVD format, and turn it into a present for your sister, because it will ensure that her valuable records are preserved forever. And you can quietly get a copy for yourself.
There is no harm in playing to the N needs of N people, if it gets you something that is both good and healthy for you, imho. Praise her for being open hearted and generous, and offer to bring the nibbles, if she wants. Give her all the attention she can possibly want, as long as she is giving you what you want. You are not trying to hurt anyone, or deprive anyone, or lie to anyone, so there is no harm in seeing these films.
I know this might sound as if you are using your sister, but in the normal world, with normal people, you would not need to play games. Family history belongs to everyone in the family, and so should these films. But Ns are all about power and control, and achieving emotional supply. So, decide to pay this time, as long as she pays her share as well.
I wish you well.
