Hello, and thank you for your kind words! I think that would make for a wonderful set-up for the adventure, though it may say something interesting about Fred’s life if the player characters are a halfling, an elf, and a half-orc ;)
This certainly would give the players a reason to help Fred out, and perhaps Alice could be omitted, or maybe she’s another sibling, or a neighbour of Fred’s who looked after him as he got older. Your idea id very whimsical and I could see it fitting in very nicely in a fairytale-like game such as Gavin Norman’s upcoming Dolmenwood setting. If Fred was indeed a wizard I think you could also hide his spellbook somewhere in the cottage, a gift for any of his children who would want to follow in his footsteps.
Thank you for your message, and for playing!