This man can't be Ida's father

Looks to me like the problem is bigger than that. Ida the daughter of Lantfried is more often said to have been born, say 763 or somewhere in that neighborhood - although any date is a pure guess.

What seems even more improbable is that the same woman married Hugues III de Montfort-sur-Risle in the 11th century, and also married Eckbert von Merseburg in the 8th century.

I'll change Ida's date of birth, and do some light clean up but this looks like a place where we need some real research ;)