Why is the "ei" necessary? The hints translate it as "his" giving us she got his brought up there...She was brought up there. This does not make sense to me.
Ei can either be his or her, the exact meaning depends on the rest of the sentence.
For the passive sentence we use the above structure.
eg She was born = Gaeth hi ei geni (lit:- she had her birth)
She was brought up = Gaeth hi ei magu (lit:- she had her bringing up)
Other passive sentences also use this construction:-
She was injured = Gaeth hi ei hanafu (lit: she had her injuring)
She was paid = Gaeth hi ei thalu (lit:- she had her paying)
This use of a possessive pattern in forming a passive with cael is explained in the notes for the section 'Brought up'. The possessive pattern itself is explained in the notes for the section 'Possession'.
If it is ei (his), it causes a soft mutation. ei (hers) causes an aspirate mutation, or adds -h- in front of a following vowel:
- Gaeth e ei fagu - He was brought up (magu)
- Gaeth hi ei magu - She was brought up
- Gaeth e ei arestio - He was arrested (arestio)
- Gaeth hi ei harestio - She was arrested
- Gaeth e ei dalu - He was paid (talu)
- Gaeth hi ei thalu - She was paid