These are all just guesses and aren’t actually confirmed, let me know what あなた think.
Humphrey - 22
it’s obvious that he is young
Kate - 20
it think she is younger than Humphrey because when they are kids she sounds less mature
Lilly - 18
Lilly is defiantly a few years younger than Kate
Garth - 20
due to an arranged marriage I would guess Garth is the same age as Kate.
Marcel - 47
I would assume Marcel is middle aged
Paddy - 40
Paddy is also probably middle aged
Winston - 54
Winston is Kate and Lilly’s father so he would have to be at least 40.
Tony - 64
Tony is Garth father so would also have to be at least 40, however he seems to have back problems something that old people get a lot
Eve - 47
Yet again Eve would have to be at least 40, but I think she’s probably slightly younger than Winston.