It's perfect! You can also use "del figlio" instead of "di suo figlio" (in questo caso "suo" è implicito)
Oh, anyway: someone told me that, to be orthodox, the epenthetic consonant "d" in ed, od, ad, could be used when the vowel that follows differs from the preceding one. That's it, "ad andare", "ed entrare", "occidente od oriente", ma "a immaginare", "e importante", "o altro"