Agatha Harkness also has links to Wanda and Vision’s children, twin sons Tommy and William.
Sometime later, after the children were claimed reabsorbed by the demon Mephisto, Harkness wiped Wanda’s memories of the boys to ease her pain of losing them.
In the comics, Wanda used magic conjured from Agatha’s astral form to conceive the two boys.
WandaVision has shown that (at least at some point) the pair will have two babies, though it’s unclear how things will play out for them.