Comparison of adjectives: the + superlative degree of the adjective + of/other...

[Djoardar1969]

Hi,

In most cases, we use "....the +(superlative degree of the adjective)+ of/other preposition....". But I got confused with these sentences.

Which one is correct (very much interested to know why)?

Alfred is the wiser of the two boys.
Or,
Alfred is the wisest of the two boys.

Again,

Julia is the elder of my two daughters
Or,
Julia is the eldest of my two daughters.

Thanks,

Debasish

[Mister Micawber]

Alfred is the wiser of the two boys.
Julia is the elder of my two daughters
_________________
Native English teacher at Mister Micawber's