grandfather of or to two children? [closed]

What do these mean?

  1. He's a grandfather of two.
  2. He's a grandfather to two.

Solution 1:

If the relationship is biological, it's "of":

"He's a grandfather of two." "She's the mother of triplets."

If the relationship is metaphorical, it's "to":

"Ralph is 'grandpa' to 75 inmates." "That dog is the mother to those ducklings."

If the relationship is created, it's either/or:

"He is the husband of/to four wives." "They are the adoptive parents of/to three siblings." US.