Background: I am estranged from my sister. The last time I had a substantial conversation with her was ~4 months ago, and her response the last time I initiated contact, via text about ~3 months ago, cemented my feelings about this. I have zero interest in being in contact with her and believe this is best for my mental health and relationships with other family members. She is well aware of what the problem is, but I have not explicitly told her I am blocking her texts, etc., mainly because I don't see a benefit (well, until now), and because I am afraid of how my parents would react. We are both in our 20's and do not live at home, but she visits home (parents' house) frequently and is close to my mother.
Story: I was not at my parents' house for Christmas Day, but visited later and gave presents to everyone. I had gotten a small gift for her in the event she would be there too, but she wasn't. I ended up leaving it at the house since she visits frequently (I think this may have been a mistake). She didn't seem to have left a gift for me, so I assumed she just hadn't gotten me anything because she knew we wouldn't see each other - this would have been fine with me, and what I would have done too if I had known.
I blocked text notifications from her a while ago, but an app update messed up my settings, and I saw this one:
Thanks for the scarf! Your Christmas present will also be at home for when you are home next.
Based on the timing, it seems like she probably got me a gift after she realized I had left one for her. Regardless, I have no interest in whatever it might be, and I do not plan to go home for quite a while (at least 4 months, probably longer).
It's worth noting that she did the same thing for my birthday. She said she got me a present and needed my address; I told her don't bother, and didn't give my address; she kept the gift for the next several months until we were both home at the same time. I had been hoping that after all that time she would realize I really didn't want it.. It was very awkward and I took the gift to end the interaction, but felt very uncomfortable about it. I donated the item and plan to do the same with any future gifts - but I'd much prefer that there weren't any to begin with.
My goal is to refuse the gift and discourage her from doing this again. I think this means I need to contact her directly, but I don't know how to without her thinking that I'm open to having a conversation. I'd also like to avoid being any more hurtful than necessary. (Because it's the right thing to do, and selfishly, because she will probably tell my mother.) Obviously I have strong feelings here, so I'm having a hard time figuring out how to express all this appropriately.
How can I refuse the gift, with minimal drama?