The version in the "sources" pans out like this
* James "Riveagh" Darcy, d 1603, President or Vice-President of Connaught, married twice
** son of James Darcy
*** Anastasia Darcy, m James Daly of Carrownakelly
**** Denis Daly, judge, 1638-1721, ancestor of the barons of Dunsandle
**** James Daly of Raford, younger brother of the judge
***** Denis Daly of Raford, m his half 3rd cousin Anastasia Darcy
** Patrick Darcy, of Kiltullagh, youngest son of James (by 2nd wife), 1598-1668, lawyer
*** James Darcy, 1633-1692
**** Hyacinth Darcy, d 1743
***** Anastasia Darcy, m her half 3rd cousin Denis Daly of Raford
So the two Denis Dalys are uncle and nephew and the two Anastasias are half 1st cousins 2x removed. Nothing obviously wrong. But who's William?
(There was at least one more Anastasia Darcy, maybe several).