@Swimpy,
Thanks, Swimpy (from both of us).
It is a good concept, if they could meet - that's what I thought/think (or better: what I think/though to salve my conscience).
However: all the times they've met (in the home), my mother was trying to "convince" her very loudly about what she should do and what not - ending usually that my aunt cried and wanted mother to leave.
Today, I could speak, for a quite longer period with my aunt. (She told me as well that she wants to die/will die soon.) She asked, where mother is. When I replied that mother had fallen again a couple of times, had to be at the hospital for checking ("nothing serious happened to her"), but can't walk ("you know, she would never use a wheelchair") but that I or a nurse would accompany her to visit aunt when mother feels better - then my aunt replied: "She had been here some time ago. All the time she's speaking only very loud ..."
So, I suppose, my aunt just wants to know where mother is, if she's still alive, if she's at a safe place.
Mother didn't ask about aunt for a couple of days - I didn'r raise this topic.
Mother stays in her room now all the time (gets her meals there). I felt, and this was confirmed by the nurses, that she isn't discontent with this. (Nurses like the meals in her room: they can thus better check that and what she eats [mother always thinks and though that she's fat].)
So, we'll wait and see if and when they want to meet/can meet.
[As an aside: though I don't have any contact at all with my sister since more than one year, I informed her with a letter about aunt's situation. In as short and official words as I could.]